• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.1
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• pp.35-39
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• 2001

Multibeam echosounder data, collected to investigate seabed features and topography, are usually subject to outliers resulting from the ship's irregular movements and insufficient correction for pressure calibration to the positions of beams. We introduce a statistical method which adjusts the outliers using the ARMA (Autoregressive Moving Average) technique. Our method was applied to a set of real data acquired in the East Sea. In our approach, autocorrelation of the data is modeled by an AR (1) model. If an observation is substantially different from that obtained from the estimated AR (1) model, it is declared as an outlier and adjusted using the estimated AR (1) model. This procedure is repeated until no outlier is found. The result of processing shows that outliers that are far greater than signals in amplitude were successfully removed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1521-1528
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• 2012

The present paper provides the elastic stress intensity factors (SIFs) and the crack opening displacements (CODs) of a thick-walled pipe with a slanted axial through-wall crack. For estimating these elastic fracture mechanics parameters, systematic three-dimensional elastic finite element (FE) analyses were performed by considering geometric variables, i.e., thickness of pipe, reference crack length, and crack length ratio, affecting the SIFs and CODs. As for loading condition, the internal pressure was considered. Based on the FE results, the SIFs and CODs of slanted axial through-wall cracks in a thickwalled pipe along the crack front and the wall thickness were calculated. In particular, to calculate the SIFs of a thick-walled pipe with a slanted axial through-wall crack from those of a thick-walled pipe with an idealized axial through-wall crack, a slant correction factor representing the effect of the slant crack on the SIFs was proposed.

• Fisheries and Aquatic Sciences
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• v.11 no.2
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• pp.103-112
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• 2008

Compressional sound velocities of shelf sediments in the South Sea of Korea, were measured in situ and in the laboratory for six cores. In situ sound velocity was measured using the Acoustic Lance (frequency of 7.5-15 kHz), while laboratory velocity was measured by the pulse transmission technique (frequency of 1MHz). Physical properties were relatively uniform with sediment depth, suggesting little effect of sediment compaction and/or consolidation. Average in situ velocity at each core site ranged from 1,457 to 1,488 m/s, which was less than the laboratory velocity of 1,503 and 1,604m/s. In muddy sediments the laboratory velocity was 39-47 m/s higher than in situ velocity. In sandy sediments, the difference was greater by an average of 116 m/s. Although the velocity data were corrected by the velocity ratio method based on bottom water temperature, the laboratory velocity was still higher than the in situ velocity (11-21 m/s in muddy sediments and 91 m/s in sandy sediments). This discrepancy may be caused by sediment disturbance during core collection and/or by the pressure of Acoustic Lance insertion, but it was most likely due to the frequency difference between in situ and laboratory measurement systems. Thus, when correcting laboratory velocity to in situ velocity, it is important to consider both temperature and frequency.

• Journal of the Korean Chemical Society
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• v.16 no.6
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• pp.341-348
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• 1972

The significance of the curvature dependency correction of surface tension is studied in calculating the pore volume distribution of porous adsorbent from nitrogen adsorption isotherm. That is, Kelvin radii are calculated with curvature dependent surface tension values calculated by Chang et al, and then with these Kelvin radii, pore volume distributions of three porous adsorbents, silica alumina (steam deactivated), silica gel (Davidson 59), and silica gel (Mallinc-krodt Standard Luminescent), are calculated. The results are compared with those obtained by the previous method in which surface tension is taken as constant and also with the others. obtained by the modelless method proposed by Brunauer et al. The maximum point of the distribution curve shift to the larger pore radius, when the curvature dependency is considered. Furthermore, the relative pressure at which capillary condensation commences is by far the lower than that accepted previously. This effect becomes significant as the pore radius approaches to the micropore range.

• Journal of Chest Surgery
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• v.23 no.3
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• pp.474-481
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• 1990

We have experienced 44 cases of coarctation of aorta in the age of infancy and children from April 1986 to September 1989 at Seoul National University Children`s hospital. Patients were thirty males and fourteen females, and their age ranged from one month to ten years[mean 23.84 $\pm$33.06 months] with thirty-two infant cases. In the infantile age, congestive heart failure was the most common chief complaint[18/32], and above that age, frequent upper respiratory infection was most common[8/12]. We experienced thirteen cases of isolated COA, twenty-two cases of COA with VSD, eight cases of COA with VSD, eight cases of COA with intracardiac complex anomalies and one case of COA with atrial septal defect. The associated intracardiac complex anomalies were three Taussig-Bing type double outlet right ventricle, one single ventricle, one transposition of great arteries, one atrioventricular septal defect, one hypoplastic aortic arch with left heart hypoplasia, and one Tetralogy of Fallot. Operative techniques of COA were twenty-three subclavian flap arterioplasty, 12 resection and end to end anastomosis, eight onlay patch angioplasty, and I direct angioplasty after resection of web. Among the cases with other cardiac anomalies, staged operation was done in twenty-nine patients, and single stage total correction was performed only in three patients. There were seven operative mortality[15.9%], all being in infantile age group, and among fourteen cases associated with large VSD[Qp/Qs>2.0, mean pulmonary arterial pressure>50mmHg], four patients were died, but there was no mortality in patients with small VSD. With above results, we are intended to discuss about the interval between staged operation, the fate of VSD after coarctoplasty in case of COA with VSD, causes of death, complications etc.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.59-67
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• 2016

Numerical simulations have been performed to investigate thrust characteristics of a through-type pintle nozzle with or without flow separation at various operating altitudes. The low Reynolds number $k-{\varepsilon}$ with compressibility correction proposed by Sarkar are applied. The detail flow structures are observed and static pressures along nozzle wall are compared with experimental results. The flow separation in the pintle nozzle disappears and jet plume strongly expands as its operating altitude increases. To evaluate the thrust characteristics, the momentum term and pressure term of thrust are analyzed. Thrust and thrust coefficient at altitude 20 km are about 10% more than them at the ground 0km.

• Journal of the Korean Magnetics Society
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• v.26 no.1
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• pp.24-30
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• 2016

MFL (Magnetic flux leakage) type nondestructive testing has been used for inspection of underground gas pipelines to find metal defects by detecting magnetic leakage signal. Because the underground gas pipeline is exposed by environment such as high pressure with great humidity, external defects are easily formed on the surface of pipelines and they are being grouped respectively. These adjacent defects cause the signal distortion of leakage flux so that it is hard to estimate the shape information of defects. In this paper, we performed to study of the signal distortion and compensating method for multiple defects in MFL type nondestructive testing system by using 3D FEM simulation. This paper proposes the basic algorithm of defect signal analysis on multiple defects on the surface of 30 inch diameter pipeline.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.3
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• pp.195-203
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• 2019

Since the hypersonic intake is directly related to the overall performance of the engine, it is essential to analyze performance characteristics under various off-design conditions. In this paper, Busemann intake and conical intake with external compression were designed, and numerical simulations were performed at on/off-design conditions. Based on the results, the overall performance characteristics of two types of intake were analyzed in various Mach numbers and angle of attacks. The results showed that performance degradation of Busemann intake with truncation angle of 2 degrees was minimal. Also, the performance of Busemann intake was higher than external compression intake at various Mach numbers, however, the starting characteristics were significantly reduced with an angle of attack.

• Physical Therapy Rehabilitation Science
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• v.10 no.2
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• pp.147-155
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• 2021

Objective: This study is to investigate the effect of real-time feedback from the therapist on posture, muscle strength, pain of subjects with forward head posture based on a non-face-to-face complex exercise program. Design: Two-group pretest-posttest design. Methods: Thirty healthy men and women in their twenties with forward head posture with a Craniovertebral angle of 52° or less were targeted, the final selection was made as 15 experimental groups who performed the non-face-to-face intervention program while receiving real-time feedback and 15 control subjects who performed the non-face-to-face intervention program without providing feedback. Six of them were eliminated, and a total of 24 were conducted as subjects. All exercise groups performed an exercise program three times a week, 30 minutes each, for a total of two weeks. Before and after exercise, Craniovertebral angle (CVA), CranioRotation angle (CRA), muscle strength, and tenderness threshold were evaluated. Results: Significant differences were shown in both groups in CVA, and tenderness threshold before and after exercise (p<0.05), and CRA, the left middle trapezius muscle strength, only in the experimental group (p<0.05). In the comparison of theamount of change between exercise groups, the group that received feedback on CVA, CRA and tenderness threshold showed a significant change than the group without feedback (p<0.05). Conclusions: As a result of this study, it can be seen that the therapist's real-time feedback is more effective in improving the forward head posture. This requires feedback from the therapist on posture correction during non-face-to-face exercise intervention.

• Journal of Veterinary Science
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• v.21 no.1
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• pp.8.1-8.11
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• 2020

This study reports the clinical use of two sevoflurane-based anesthetic techniques in dogs undergoing craniectomy. Twenty-one animals undergoing elective rostrotentorial or transfrontal craniectomy for brain tumor excision, anesthetized with sevoflurane, were enrolled in this retrospective, observational study. Anesthetic records were allocated to two groups: Sevo-Op (sevoflurane and short acting opioid infusion): 8 dogs and Sevo-Dex (sevoflurane and dexmedetomidine infusion): 13 dogs. Average mean arterial pressure (MAP), heart rate, end-tidal carbon dioxide, end-tidal sevoflurane and intraoperative infusion rates during surgery were calculated. Presence of intra-operative and post-operative bradycardia, tachycardia, hypotension, hypertension, hypothermia, hyperthermia was recorded. Time to endotracheal extubation, intraoperative occurrence of atrioventricular block, postoperative presence of agitation, seizures, use of labetalol and dexmedetomidine infusion were also recorded. Data from the two groups were compared with Fisher's exact test and unpaired t tests with Welch's correction. Odds ratio (OR) and 95% confidence interval (CI) were calculated for categorical variables. Intra-operatively, MAP was lower in Sevo-Op [85 (± 6.54) vs. 97.69 (± 7.8) mmHg, p = 0.0009]. Time to extubation was longer in Sevo-Dex [37.69 (10-70) vs. 19.63 (10-25), p = 0.0033]. No differences were found for the other intra-operative and post-operative variables investigated. Post-operative hypertension and agitation were the most common complications (11 and 12 out of 21 animals, respectively). These results suggest that the infusion of dexmedetomidine provides similar intra-operative conditions and post-operative course to a short acting opioid infusion during sevoflurane anesthesia in dogs undergoing elective rostrotentorial or transfrontal intracranial surgery.