• Bulletin of the Korean Mathematical Society
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• v.50 no.3
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• pp.935-949
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• 2013

In this paper, we study surfaces in $\mathb{E}^3$ whose Gauss map G satisfies the equation ${\Box}G=f(G+C)$ for a smooth function $f$ and a constant vector C, where ${\Box}$ stands for the Cheng-Yau operator. We focus on surfaces with constant Gaussian curvature, constant mean curvature and constant principal curvature with such a property. We obtain some classification and characterization theorems for these kinds of surfaces. Finally, we give a characterization of surfaces whose Gauss map G satisfies the equation ${\Box}G={\lambda}(G+C)$ for a constant ${\lambda}$ and a constant vector C.

• Communications of the Korean Mathematical Society
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• v.9 no.3
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• pp.503-511
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• 1994

In this paper, the ring A will mean a commutative Noetherian ring with non-zero multiplicative identity, it is understood that the ring homomorphisms respect identity elements and M will denote an A-module. Throughout this paper A and B will denote rings, $f : A \to B$ a ring homomorphism. C(A) (resp. C(B)) presents the category of all A-modules (resp. B-modules) and A-homomorphisms (resp. B-homorphisms) between them. The following ideas will be used without further explanation. B can be regarded as an A-module by means of f and $M\otimesB$ can be regarded as a B-module in the natural way. Furthermore the restriction of scalars provides a functor from C(B) to C(A).

• Reproductive and Developmental Biology
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• v.28 no.4
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• pp.227-233
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• 2004

This study was conducted to investigate the effect of various addition and exclusion time of glucose (Control: no addition, A: 24～72 h, B: 24～48 h, C: 48～72 h, D: 0～72 h, E: 0～48 h, F: 0～24 h and 48～72 h, G: 0～24 h) on embryonic developmental capacity of 2-cell embryos in mice. Developed blastocysts were assessed for mean cell number by differential staining. The zona-intact blastocyst (ZiB) rates were higher (p<0.05) in group B than control. However, the zona-escape blastocyst (ZeB) rates were not significantly different in all groups. At 72 h, total blastocyst (ZiB + ZeB) formation rates were not significantly different in all groups. The mean cell number was not significantly different among all groups. The inner cell mass (ICM) cell number was higher (p<0.05) in group F than control, group A, B and G. The trophectoderm (TE) cell number was higher (p<0.05) in control than group A and D. The %ICM was higher (p<0.05) in group C, D and F than control. The ICM : TE ratio was not significantly different in all groups. Between control and glucose group, no significant difference was observed in the total blastocysts (ZiB + ZeB) formation rates. Also, no significant difference was observed in the mean cell number, ICM cell number and ICM : TE ratio. However the TE cell number was higher (p<0.05) in control than glucose group and %ICM was higher (p<0.05) in glucose group than control. In conclusion, glucose added in culture medium was not inhibitory on blastocyst formation but glucose added for 48 ～72 h in culture medium increases %ICM of blastocysts in mice.

• The Korean Journal of Emergency Medical Services
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• v.4 no.1
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• pp.47-55
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• 2000

The study was conducted to investigate the burnout of firefighters. The subjects were 223 firefighters in C-Do. The instruments used for this study were a survey of general characteristics(10 items), burnout(23 items). Analysis of data was done by use of mean percentage, t-test, ANOVA, stepwise multiple regression with SAS program. The results of this study are as follows; 1. Burnout according to general characteristics were showed significant difference in job-aptitude(F＝6.30, P<.001), health status(F＝5.92, P<.001), education(t＝6.09, P<.01), working place rotation(t＝2.59, P<.01), call number/week(F＝3.28, P<.01), job-burden(F＝4.45, P<.01), paper-job burden(F＝3.87, P<.05). 2. Category score of burnout were showed the higher score in the lowed personal accomplishment(3.29). 3. Category score of burnout according to aptitude were showed difference each other. 4. Predicting factor of burnout were paper-job burden, health status, job-burden(20.99%).

• Journal of the Korean Society of Industry Convergence
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• v.1 no.2
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• pp.41-48
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• 1998

This experimental study describes atomization characteristics of spray-spray impingement. Effect of the impingement location and angle on the penetration and the sauter mean diameter of the impinged spray were investigated. Experiment were performed under ranging from 50kPa to 250kPa spray pressure, ranging $30^{\circ}C$ to $135^{\circ}C$ angle on the penetration and free spray. In the case of this experimental, sauter mean diameter $D_{32}$ tends to decrease and duration of film disintegration $t_f$ to decrease, when spray pressure and angle on the penetration is increased. Sauter mean diameter $D_{32}$ were about 20% to be smaller compared with a free spray to jet-jet impingement and 30% to be smaller compared with a free spray to spray-spray impingement.

• Communications of the Korean Mathematical Society
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• v.18 no.3
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• pp.481-484
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• 2003

We will show that if U is a Bergman ball E($\alpha;\;\delta$) in $B_n\;\subset\;{\mathbb{C}_n}$ and if U has M-harmonic volume mean value property at a for all M-harmonic functions f on $\={U} $, then U must be a ball centered at the origin with $\alpha\;=\;0$.

• Korean Journal of Radiology
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• v.23 no.2
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• pp.180-188
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• 2022

Objective: To validate the performance of 3T spin-echo echo-planar imaging (SE-EPI) magnetic resonance elastography (MRE) for staging hepatic fibrosis in a large population, using surgical specimens as the reference standard. Materials and Methods: This retrospective study initially included 310 adults (155 undergoing hepatic resection and 155 undergoing donor hepatectomy) with histopathologic results from surgical liver specimens. They underwent 3T SE-EPI MRE ≤ 3 months prior to surgery. Demographic findings, underlying liver disease, and hepatic fibrosis pathologic stage according to METAVIR were recorded. Liver stiffness (LS) was measured by two radiologists, and inter-reader reproducibility was evaluated using the intraclass correlation coefficient (ICC). The mean LS of each fibrosis stage (F0-F4) was calculated in total and for each etiologic subgroup. Comparisons among subgroups were performed using the Kruskal-Wallis test and Conover post-hoc test. The cutoff values for fibrosis staging were estimated using receiver operating characteristic (ROC) curve analysis. Results: Inter-reader reproducibility was excellent (ICC, 0.98; 95% confidence interval, 0.97-0.99). The mean LS values were 1.91, 2.41, 3.24, and 5.41 kPa in F0-F1 (n = 171), F2 (n = 26), F3 (n = 38), and F4 (n = 72), respectively. The discriminating cutoff values for diagnosing ≥ F2, ≥ F3, and F4 were 2.18, 2.71, and 3.15 kPa, respectively, with the ROC curve areas of 0.97-0.98 (sensitivity 91.2%-95.9%, specificity 90.7%-99.0%). The mean LS was significantly higher in patients with cirrhosis (F4) of nonviral causes, such as primary biliary cirrhosis (9.56 kPa) and alcoholic liver disease (7.17 kPa) than in those with hepatitis B or C cirrhosis (4.28 and 4.92 kPa, respectively). There were no statistically significant differences in LS among the different etiologic subgroups in the F0-F3 stages. Conclusion: The 3T SE-EPI MRE demonstrated high interobserver reproducibility, and our criteria for staging hepatic fibrosis showed high diagnostic performance. LS was significantly higher in patients with non-viral cirrhosis than in those with viral cirrhosis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2136-2149
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• 1992

The natural convection from an inclined ice flat plate immersed in cold water near its density maximum is studied numerically. Finite difference analysis has been performed for the heat and momentum transfer with respect to various inclined angles and ambient water temperatures. The results of the analysis are presented for ambient water temperatures, 1.0deg. C. leq. T／sub .inf.／.leq. 15.0deg. C and the inclined anales from 0deg to 60deg. They include velocity profiles, temperature profiles, melting velocities, and mean Nusselt numbers for entire flow fields, Generally, in the range of 0deg. C .leq.theta. .leq. 60.deg. C, the results show three distinct flow regimes, In the range of 1.0 deg. C .leq. T／sub .inf.／ .leq. 4.6 .deg. C, the greatest mean Nuselt number exists about 3.0deg. C. In the range of 5.7deg. C .leq. T／sub .inf.／ .leq. 15.0deg. C, mean Nuselt number increases as ambient water temperature increases. Also, the mean Nuselt number decreases as the inclined angle increases. This theoretical results are compared with previous experimental ones and multiple steady state ones.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.3 no.2
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• pp.285-297
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• 1996

This study has been done for the purpose of investigating the degrees of death orientation and terminal care performance. The factors related to these two variables, and the relationship between death orientation and terminal care performance. The subjects of study were 128 nurses who implemented nursing care for terminally ill patients at C University Hospital in Kwang Ju city. The data were collected from March 13 to 19, 1996, by means of Death Orientation by Thorson Powell(1988) and Terminal Care Performance Scale by researcher. The data were analysed by t-test, ANOVA, Duncan test and Pearson's correlation coefficient. The Results of this study were summarized as follows : 1. The mean score of death orientation was 61.4. The degree of death orientation showed no significant difference depending on the general characteristics of nurses. 2. The mean score of terminal care performance was 45.5. In comparison of the degree of terminal care performance among three domains, the mean score of each item tended to show higher degrees in order of 'Psychological domain(2.4)', 'Physical domain(2.2)', 'Spiritual domain(1.9)'. 3. The degree of terminal care performance showed significant differences in age(F=11.48 p=.0001), marital status(t=10.49 p=.0015), religion(t=5.01 p=.0270), period of clinical experience(F=10.30 p=.0001) and ward unit(F=3.73 p=.0036). The degree of terminal care performance in physical domain showed significant differences in age(F=7.26 p=.0010), marital status(t=9.72 p=.0023), period of clinical experience(F=7.03 p=.0013), ward unit(F=6.23 p=.0001). The degree of terminal care performance in psychological domain showed significant differences in age(F=8.73 p=.0003), marital status(t=4.22 p=.0419), religion(t=5.59 p=.0196), period of clinical experience(F=6.36 p=.0023), ward unit(F=3.33 p=.0075). The degree of terminal care performance in spiritual domain showed significant differences in age(F=8.30 p=.0004), marital status(t=10.45 p=.0016), religion(F=5.41 p=.0216), period of clinical experience(F=8.80 p=.0003). 4. The relationship between the degrees of death orientation and terminal care performance showed no correlation(r=-.026 p=.7746).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.3
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• pp.147-154
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• 1992

Laminar natural convection heat transfer from a hot body in a square enclosure has been studied for various center positions of a hot square at Grashof number $Gr=1.5{\times}10^5$, Prandtl number Pr=0.71 and dimensionless thermal conductivity $k_g/k_f=14710$. The natural convection at the center position of a hot square; $X_c$, $Y_c=0.5$, 0.2 shows the most strong and at $X_c$, $Y_c=0.5$, 0.7 the most weak. The total mean Nusselt number at $X_c$, $Y_c=0.5$, 0.2 was 7.4% higher than that at $X_c$, $Y_c=0.2$, 0.5. The total mean Nusselt number at $X_c$, $Y_c=0.5$, 0.7 was 5.0% lower than that at $X_c$, $Y_c=0.3$, 0.5.