• East Asian mathematical journal
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• v.32 no.1
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• pp.93-100
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• 2016

The generalized Gaussian image of a spacelike surface in $L^n$ lies in the indefinite positive quadric ${\mathbb{Q}}_+^{n-2}$ in the open submanifold ${\mathbb{C}}P_+^{n-1}$ of the complex projective space ${\mathbb{C}}P^{n-1}$. The purpose of this paper is to find out detailed information about ${\mathbb{Q}}_+^{n-2}{\subset}{\mathbb{C}}P_+^{n-1}$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.761-768
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• 2000

In order to investigate how the fatigue damage effects on the critical properties of superconductor, a fatigue test at room temperature and an Ic measurement test at 4.2K were carried out in this study, respectively, using a 9 strand Cu-Ni/NbTi/Cu composite cable. Through the fatigue test of a 9 strand Cu-NUNbTi/Cu composite cable, a conventional S-N curve was plotted even though there was a possibility of fretting among strands. It was found that the maximum stress corresponding to the inflection point on the S-N curve obtained was nearly the same value as the yielding strength of cable obtained from the static tensile test. However, the effect of cabling in multi-strands superconducting cable on the fatigue strength was not noticeable. The critical current(Ic) measurement was carried out at 4.2K in a NbTi strand out of the fatigued cable. It showed a degradation of lc at high stress amplitude regions over 380NTa, and the degradation became significant as the applied stress amplitude increased.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1663-1672
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• 2018

In recent times, gas insulated medium voltage (MV) circuit breakers (CB) form a vital component in power system network, considering its advantages such as reduced size and safety margins. Gas insulation characteristics of circuit breakers are generally measured by lightning impulse (LI) test according to IEC standard 60060-1 as a factory routine test. Considering the environmental issues of $SF_6$ gas, many research works are being carried out towards the mixture of $SF_6$ gases for high voltage insulation applications. However, few reports are only available regarding the LI withstand and streamer propagation characteristics (at both positive and negative polarity of waveform) of $SF_6/N_2$ gas mixture insulated medium voltage circuit breakers. In this paper, positive and negative polarity LI tests are carried out on 22 kV medium voltage circuit breaker filled with $SF_6/N_2$ gas mixture at different gas pressures (1-5 bar) and at different gas mixture ratios. Important LI parameters such as breakdown voltage, streamer velocity, time to breakdown and acceleration voltage are evaluated with IEC standard LI ($1.2/50{\mu}s$) waveform. Weibull distribution analysis of LI breakdown voltage data is carried out and 50% probability breakdown voltage, scale parameter and shape parameter are evaluated. Results illustrate that the $25%SF_6+75%N_2$ gas filled insulation considerably enhances the LI withstand and breakdown strength of MV circuit breakers. LI breakdown voltage of circuit breaker under negative polarity shows higher value when compared with positive polarity. Results show that maintaining the gas pressure at 0.3 MPa (3 bar) with 10% $SF_6$ gas mixed with 90% $N_2$ will give optimum lighting impulse withstand performance of 22 kV MV circuit breaker.

• Korean Journal of Veterinary Research
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• v.32 no.4
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• pp.457-462
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• 1992

This study was carried out to investigate the branches and distribution of Nervus ophthalmicus of the Korean native goat. The observation was made by dissection of embalmed cadavers of ten Korean native goats. The results were as follows; 1. N. ophthalmicus arised from the trigeminal nerve in a common trunk with the maxillary nerve. 2. At the exit of the foramen orbitorotundum the N. ophthalmicus gave off Ramus zygomaticotemporalis, N. frontalis, Ramus sinuum frontalium and N. nasociliaris. 3. Ramus zygomaticotemporalis, after giving off N. lacrimalis, left the orbital cavity and gave off Rami cornuales which were distributed the caudolateral part of the base of the horn. 4. After giving off N. ciliaris longus and Ramus communicans cum ganglio ciliari, N. nasociliaris divided into N. ethmoidalis and N. infratrochlearis which gave off Rami cornuales.

• Korean Journal of Soil Science and Fertilizer
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• v.9 no.4
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• pp.245-250
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• 1976

A field study was conducted to find out the optimum level of NPK fertilizers for pearl barley (Coix Lacryma-Jobi L.). The results are sumarized as follows. 1. When all of NPK fertilizers were increased together as 0-0-0, 6-3-3, 12-6-6-6 and 18-9-9 kg/10a of NPK, the grain yield also increased lineally. 2. When the level of two other elements were fixed at 12kg/10a for N and 6kg/10a for P and K, maximum yields were obtained at 12kg/10a of N and 6kg/10a of P and K. 3. Accordingly, with present results, it is difficult to point out the optimum levels of NPK. It seemed necessary to conduct another trial with expanded NPK levels. However it can be pc pointed out that the yield of pearl barley can be increased with higher levels of NPK fertilizers than 18-9-9 kg/10a at the similar soil used for present study. 4. The antagonism phenomena were observed between N and K in plant's uptake.

• Bulletin of the Korean Mathematical Society
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• v.35 no.1
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• pp.25-32
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• 1998

Let N be the 3-dimensional Heisenberg group equipped with a left-invariant metric on N. We characterize the Jacobi fields and the conjegate points along a geodesic on N, which points out that Theorem 4 of [1] is not correct.

• Journal of muscle and joint health
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• v.7 no.2
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• pp.227-240
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• 2000

The purpose of this article was to identify trend in Arthritis research and to provide ba an approach of Arthritis research. The results of analysis of 69 Arthritis articles public year of between 1970-1999 found that most articles(27.6%, n=19) were published since few(10.1%, n=7) were before 1994. Vast majority of articles(79.8%, n=55) were printed in The Journal of Rheumatology Health, and 79.8%(n=55) of those were quantitative research, 8.7%(n=6) were qualitative research, and 14%(n=1) was methodological research. 29.0%(n=20) of quantitative research were carried in experimental design and over half(50.8%, n=35) in nonexperimental design. Having concerned the types of treatment(or intervention) used in experimental study, the most common treatment was 'exercise' (45.0%, n=9), and other less common were 'self-help education(15.0%, n=3), home care(10.0%, n=2) supportive care(10.0%, n=2), flexibility exercise combined with local heat therapy(5.0%, n=1), relaxation training(5.0%, n=1). Of the types of exercise, aquatic exercise was 30.0%(n=6). The effect of exercise on outcome variable was found to be most strong among the other types of treatment. 18 articles of nonexperimental research were correlational research. From the analysis of correlational research, 29 concepts were identified, and the relationship between depression and other variable were strongly reported. In descriptive studies, most commonly physiological variables were examined in 5 articles(29.5%). Only one study(5.9%) explored patient's perception of the causal factors and those causality. In qualitative researches, two study were carried out by the means of grounded theory. Majority of those subjects were RA patients, and the largest number of sample were 23 and the smallest was 1 In two studies, patient's perceived causality of RA was identified as a research problems, and an experience of ADL, fatigue Phenomenon, an experience of having a total knee replacement with osteoarthritis were each found in one study. Methodological research was carried out to test validity and reliability of the RA Fatigue Scale.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4475-4483
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• 2011

This study was carried out by practical method in a subjectivity study accessible in-depth, in sloughing off old habit of functional quantity analysis about a subjectivity of fire-public servant in nation. The perception pattern come out in this study were divided into four types in Q-methodology. The result is as follows ; it is divided into 1[(N=26) : Occupational Type], 2[(N=11) : Experience Type], 3[(N=1) : Human Type], 4[(N=2) : Justice Type]. There are four types of fire fighter images. In conclusion, this study is to ascertain acceptance behavior about Reception Type on a subjectivity of fire-public servant in nation ; to offer a developmental suggestion about it.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.2
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• pp.230-236
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• 2008

Purpose: This study was performed to investigate the incidence, types of fracture, treatment, associated fracture and complications in patients with nasal bone fracture. Materials and methods: Clinical examination, patient's records and radiographic images were evaluated in 230 cases of nasal bone fractures who were treated at the Department of Oral and Maxillofacial Surgery, Chonnam National University Hospital for recent 5 years; from January 2002 to December 2006. Results: 1. The age of patient was ranged from 4 to 77 years (mean age=36.6 years); Males was 75.7% (n=174), and females 24.3% (n=56). 2. The cause of the nasal bone fracture in this study was a fall or slip down (28.8%, n=66), sports accident (26.0%, n=60), fighting (21.3%, n=49), traffic accident (9.6%, n=22), industrial trauma (7.8%, n=18), and the others (6.6%, n=15). 3. For the patterns of fracture, simple fracture without displacement occured in 10.4% (n=24). Simple fracture with displacement without septal bone fracture was found in 49.5% (n=114). Simple fracture with displacement in company with septal bone fracture showed in 32.6% (n=75). Commiuted fracture with severe depression was presented in 7.4% (n=17). 4. The reduction the displaced nasal bone was carried out in 2 to 10 days (mean 6.8 days) after the injury. 5. Nasal bone fracture associated with Le Fort I fracture (6.5%, n=6.5), Le Fort II fracture (7.4%, n=17), Le Fort III fracture (1.3%, n=3), NOE fracture (13.9%, n=32), ZMC fracture (17.4%, 40), maxillary bone fracture (8.3%, n=19), orbital blow-out fracture (15.7%, n=36), frontal bone fracture (1.3%, n=3) and alveolar bone fracture (10.9%, n=25). 6. The major type of treatment method was closed reduction in 90% (n=207), open reduction in 3% (n=7), and observation in 7% (n=16). 7. There were some complications such as ecchymosis, hyposmia, hypo esthesia and residual nasal deformity which are compatible. Open rhino-plasty was conducted for 3 patients who had residual nasal deformity. Conclusions: These results suggest that most of nasal bone fractures are occurred physically active aged groups(age 10-49 years) and could be treated successfully with closed reduction at 7 days after the injury.

• Computers and Concrete
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• v.12 no.6
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• pp.775-783
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• 2013

A novel reliability-based work model of k/n (G) system has been developed. Unit failure probability is given based on the load and strength distributions and according to the stress-strength interference theory. Then a dynamic reliability prediction model of repairable k/n (G) system is established using probabilistic differential equations. The resulting differential equations are solved and the value of k can be determined precisely. The number of work unit k in repairable k/n (G) system is obtained precisely. The reliability of whole life cycle of repairable k/n (G) system can be predicted and guaranteed in the design period. Finally, it is illustrated that the proposed model is feasible and gives reasonable prediction.