• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.5
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• pp.615-622
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• 2000

Numerical simulation is performed with Denton's code to get pressure loss coefficients in wide range of reverse flow incidence(from -90 degree to +85 degree) for an axial compressor cascade. As a results, it is found that the pressure loss coefficient is increased with incidence and there exist critical incidence which corresponds to the maximum pressure loss coefficient. Pressure loss coefficient with bigger incidence than its critical value is decreased. The effect of increasing incidence in a cascade extremely reduce the mass flow rate by the large flow separation region. Consequently this effect reduce the portion of dynamic pressure in the total pressure loss and beyond the critical incidence the pressure loss coefficient decrease.

• Solar Energy
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• v.20 no.1
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• pp.63-72
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• 2000

In this study, theoretical simulation method for the steady state characteristics of a refrigeration cycle which consists of one condenser and multi-evaporator (Multi-air conditioner) is presented. The simulation was performed for a typical multi-air conditioning system consisted one outdoor unit with air-cooled condenser, compressor, linear electric expansion valve and bypass circuit and connected three-evaporators (three indoor units). The simulation results are good agreement with those of experiments within 5 $\sim$ 10% at the given system operation conditions which are condensing pressure, evaporating pressure, sub-cooled degree of condenser, superheated degree, discharge temperature of compressor and pulse of linear electric expansion valve.

• Animal Systematics, Evolution and Diversity
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• v.12 no.4
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• pp.331-347
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• 1996

The geographic distribution and variation for Rhinogobius brunneus were surveyed by means of allozymic and morphological analyses and it was revealed that the Korean populations of R. brunneus comprise three distinct types, Type-A, Type-B, and Type-C, which show considerable differentiation to a degree of interspecific level(Rogers' S(1972): $S_{A-B}$=0.631, $S_{A-C}$=0.628, $S_{B-C}$=0.661). In addition, no evidence of gene flow among the types was found at sympatric area and it is assumed that reproductive isolation is completed. Moreover there is microhabitat segregation according to the distance from river mouth among each types and which segregation was regarded as a factor to facilitate reproductive isolating mechanism. Therefore, based on the evidence presented above, these three types of R. brunneus are considered as typical discrete species.

• Korean Journal of Human Ecology
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• v.24 no.4
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• pp.555-569
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• 2015

During a design process of a protective equipment for sports activities, minimizing movement restrictions is important for enhancing its functions particularly for protection. This study presents a three-dimensional(3D) modeling methodology for designing baseball catcher's leg guards that will allow maximum possible performance, while providing necessary protection. 3D scanning is performed on three positions frequently used by a catcher during the course of a game by putting markings on the subject's legs at 3cm intervals : a standing, a half squat with knees bent to 90 degrees and 120 degrees of knee flexion. Using data obtained from the 3D scan, we analyzed the changes in skin length, radii of curvatures, and cross-sectional shapes, depending on the degree of knee flexion. The results of the analysis were used to decide an on the ideal segmentation of the leg guards by modeling posture. Knee flexions to 90 degrees and to $120^{\circ}$ induced lengthwise extensions than a standing. In particular, the vertical length from the center of the leg increases to a substantially higher degree when compared to those increased from the inner and the outer side of the leg. The degree of extension is varied by positions. Therefore, the leg guards are segmented at points where the rate of increase changed. It resulted in a three-part segmentation of the leg guards at the thigh, the knee, and the shin. Since the 120 degree knee-flexion posture can accommodate other positions as well, the related 3D data are used for modeling Leg Guard (A) with the loft method. At the same time, Leg Guard (B) was modeled with two-part segmentation without separating the knee and the shin as in existing products. A biomechanical analysis of the new design is performed by simulating a 3D dynamic analysis. The analysis revealed that the three-part type (A) leg guards required less energy from the human body than the two-part type (B).

• Journal of Haehwa Medicine
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• v.6 no.1
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• pp.555-566
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• 1997

This study was undertaken to identify the degree of burden and depression according to level of self-care activity and variables to which affect that in family caregivers of patients with stroke. The data were collected from October 23th to November 20th, 1995 The subjects in this study were 80 caregivers, that is, one family member and 80 patients with stroke who were hospitalized in one oriental medicine hospital in D city. The questionnaires consisted of questions regarding burden(13 items, 6 point scale), depression(20 items, 4 point scale), and self-care activity(15 items, 5 point sacle) Data were analyzed using percentages, means, t-test and ANOVA with the SAS program. The results of this study are as follows: 1) The mean score for client's self-care activity was 2.58. The highest score of the self-care activity item was 'returning'(M=3.604), and the lowest score of the self-care activity item was 'shower or tubbathing'(M=1.925). 2) the degrees of self-care activity according to the general characteristics of patients were tested. It was significantly different by sex(P<0.01), occupation(P<0.05), and relationships with patients(P<0.05). That is, the degree of self-care activity was higher in men than that of women, and caregiver with job than caregiver without that. In the case that caregiver was a patient's spouse, the degree of self-care activity was higher than other case. 3) The score for family caregiver's burden was higher than the mid level for the 13 items and caregiver's depression was relatively low. 4) According to the degree of self-care activity, the group was divided to 3, that is, A( 15-33), B(34-56), and C(57-75). The score of total burden was the highest in group A(M=55.257) and the lowest in group C(M=51.928), but there were no statistically significant differences between groups. The score of objective burden was the highest in group A(M=30.400), and the lowest in group C(M=25.214), and there were statistically significant differences between groups. The score of subjective burden was the highest in group B(M=26.000) and the lowest in group A(M=24.783), but there were no statistically significant differences between groups. The degree of depression was the highest in group A(M=44.750) and the lowest in group C(M=40.751), but there were no statistically significant differences between groups.

• Membrane Journal
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• v.29 no.5
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• pp.252-262
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• 2019

A sulfonated star branched poly(styrene-b-butadiene-b-styrene) triblock copolymer (SSBS) was synthesized with varying degrees of sulfonation. The effective sulfonation on the butadiene block was confirmed by FT-IR spectroscopy. Ion exchange capacity by titration was used to determine the degree of sulfonation. The synthesized polymer observed enhanced water uptake and proton conductivity. At room temperature, the SSBS with 25 mol% degree of sulfonation showed an outstanding proton conductivity of 0.114 S/cm, similar to that of commercial membrane, Nafion. The effect of temperature at constant relative humidity on conductivity resulted to a remarkable increase in proton conductivity. Methanol permeability studies showed a value lower than Nafion for all the sulfonated membranes. Structural nature observed using AFM showed that the membranes observed microphase separated nanostructures and the connectivity of the interionic channels.

• Korean Journal of Mathematics
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• v.31 no.2
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• pp.153-160
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• 2023

In this paper, we study the growth of polynomials P(z) of degree n defined by $P(z)=z^s(a_0+\sum\limits_{j=t}^{n-s}a_jz^j)$, t ≥ 1, 0 ≤ s ≤ n-1 which do not vanish in the disk |z| ≤ k, k ≥ 1 except for the s-fold zeros at origin. Our result generalises and refines many results known in the literature.

• Animal cells and systems
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• v.4 no.1
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• pp.23-30
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• 2000

Horizontal starch gel electrophoresis for 29 populations (n=543) of the wrinkled frog, Rana rugosa, from Korea and Japan was peformed to assess the degree of genic variation and genetic diversity, and to understand the biogeographic pattern of distribution and speciation. A sum of 22 presumptive loci was screened from 17 enzymes and general proteins. Four loci, Aco, Est-3, Me-2, and Pgm, demonstrated high levels of polymorphism. The degree of average genetic variation of R. rugosa was P=22.7% (9.1-40.9%), Ho=0.086 (0.048-0.165) and He=0.090 (0.042-0.168). In the south-eastern region of the Korean peninsula (Chongsong, Yongchon, Ulsan, Kyongju, Pohang, yongdok and Ulchin), a few unique alleles in the Mpi locus were detected and their biogeographic implications were considered. The degree of genetic differentiation among the Korean populations was moderate (S=0.900), whereas the degree of genetic diversity between Korean and Japanese populations was notably high (S=0.687, D=0.293). This result corresponds with the data obtained by the mitochondrial cytochrome b gene sequence (Lee et al., 1999) suggesting that the Korean and Japanese R. rugosa might have evolved a specific level of genetic differentiation since their geographic isolation.

• Korean Journal of Community Nutrition
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• v.8 no.5
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• pp.631-641
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• 2003

The purpose of this study was to investigate the effects of preschool children's taste preferences on their intake of nutrients and the degree of dental caries. The subjects were 126 preschool children (boys 62 and girls 64) in Daegu area. Their taste preferences and food intake were investigated and their teeth were also examined. The energy intake of boys (1550 kcal) were significantly higher than that of girls (1441 kcal). Daily dietary intakes of nutrients-except niacin and vitamin C-were higher than those of RDA. Vitamin B$_1$ intake of the group preferring a salty taste was significantly lower than that of the other group (p<0.05). Vitamin B$_2$ intake of the group preferring a salty taste was significantly higher than that of the other group (p<0.05). Vitamin C intake of the group preferring a hot taste was significantly higher than that of the other group (p<0.05). The group with a preference for sweet had more experiences of dental caries and more decayed teeth than the other group, but which is not significant. The experiences of dental caries were negatively correlated with protein intake (p<0.01). The decayed teeth were negatively correlated with energy and protein intakes (p<0.01). Our data suggested that taste preferences are associated with vitamins intake and the degree of dental caries in preschool children. It means the sweet preference increased the experiences of the dental caries.

• Communications of the Korean Mathematical Society
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• v.38 no.3
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• pp.937-941
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• 2023

For each positive integer n, a square congruence graph S(n) is the graph with vertex set H = {1, 2, 3,...., n} and two vertices a, b are adjacent if they are distinct and a² ≡ b² (mod n). In this paper we investigate some structural properties of square congruence graph and we obtain the relationship between clique number, chromatic number and maximum degree of square congruence graph. Also we study square congruence graph with p vertices or 2p vertices for any prime number p.