• ETRI Journal
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• v.45 no.4
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• pp.557-569
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• 2023

Traditional deterministic channel modeling is accurate in prediction, but due to its complexity, improving computational efficiency remains a challenge. In an alternative approach, we investigated a multilayer artificial neural network (ANN) to predict large-scale and small-scale channel characteristics in metro tunnels. Simulated high-precision training datasets were obtained by combining measurement campaign with a ray tracing (RT) method in a metro tunnel. Performance on the training data was used to determine the number of hidden layers and neurons of the multilayer ANN. The proposed multilayer ANN performed efficiently (10 s for training; 0.19 ms for prediction), and accurately, with better approximation of the RT data than the single-layer ANN. The root mean square errors (RMSE) of path loss (2.82 dB), root mean square delay spread (0.61 ns), azimuth angle spread (3.06°), and elevation angle spread (1.22°) were impressive. These results demonstrate the superior computing efficiency and model complexity of ANNs.

• Journal of Wind Energy
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• v.14 no.4
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• pp.43-49
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• 2023

We have studied biofouling in Korea's offshore wind farms by using image analysis through monitoring and surface energy analysis. To observe the biofouling characteristics, samples were fabricated using Micron extra 2 and PropOne, which have a self-polishing property, and Hempathane HS 55610, which is used in substructure coatings. The manufactured samples were installed at the bottom of a ladder in a substructure, and monitored for 10 months. The most biofouling occurred in the sample without the self-polishing property, and algae, barnacles and corallinales were observed. The surface energy analysis used the Owens-Wendt-Rabel and Kaelble (OWRK) model, which uses the contact angles of two standard fluids. As a result of calculating the surface energy using contact angle measurement, the sample without the self-polishing property showed the highest value. This result was consistent with the biofouling incidence observed through monitoring.

• Physical Therapy Korea
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• v.21 no.3
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• pp.73-79
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• 2014

The purposes of the current study were to (1) estimate the inter-rater agreement for visual assessment of scapular downward rotation (SDR), (2) develop the scapular downward rotation index (SDRI) as a method to measure SDR objectively and quantitatively, and (3) analyze the intra- and inter-rater reliability of the SDRI. Twenty subjects with scapular downward rotation syndrome (SDRS) were recruited for this study. The visual assessment and the measurement for the SDRI were conducted by two examiners in two sessions each. The SDRI [$(a-b){\div}a{\times}100$] is calculated with the measurement of two linear distances: One is a perpendicular distance from the root of the scapular spine to the thoracic mid-line (a), and the other is a perpendicular distance from the inferior angle of the scapula to the thoracic mid-line (b). Cohen's kappa coefficient was calculated to estimate the inter-rater agreement for visual assessment. Intra-class correlation coefficients (ICCs) with a 95% confidence interval (CI), the standard error of measurement, and minimal detectable differences were calculated to assess intra- and inter-rater reliability of SDR measurement using the SDRI. The results indicated that the kappa coefficient of inter-rater agreement for visual assessment was fair (${\kappa}=.21$). The intra-rater reliability of SDR measurement using the SDRI was excellent for examiner 1 (ICC=.92, 95% CI=.78~.97) and good for examiner 2 (ICC=.82, 95% CI=.55~.93). The inter-rater reliability was moderate (ICC=.73, 95% CI=.32~.89). These findings showed that SDR measurement using the SDRI for subjects with SDRS may be considered reliable and better than the visual assessment.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.5
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• pp.664-675
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• 1998

The purpose of this study was to isolate the observational error included in plane photogrammetric data and suggest more accurate and suitable method for body shape measurement. Three experiments were carried out in this study. First of all, the variables which can be obtained from photogrammetric method were selected among the data which can be measured improperly by direct measurement or showing large deviations between the samples. Secondly, the height, the width and the depth of 50 subjects were measured by plane photogrammetry. The result showed that plane photogrammetric data contain significant observational error even for the same variables, as the angle of which photos had been taken changes. Therefore, in order to reduce the observational error and to measure the human body accurately, three-dimensional measurement, stereo photogrammetry was employed in the last experiment. As it is important to isolateonly the observational error by plane photogrammetry and to exclude the accidental error caused by movement of human body subject, body shape model(manikin) was used as subject. The result showed that the average observational error by plane photogrammetry was more than 4 cm in the height, 0.85-1.29cm in the width and 0.49cm in the depth. In conclusion, it is not adequate to use the height obtained from plane photogrammetric data as human body measurement data. And the width and the depth should be used cautiously, even though they are relatively less significant, the error still can make some difference on clothing construction.

• The Journal of Korean Physical Therapy
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• v.14 no.4
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• pp.274-307
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• 2002

The TLSO was customized for this study in OO ortho-prosthesis institute from Jan. 1th., 2000 to Dec. 31th., 2000 and in order to measure effects of TLSO. 20 females in a growth period applicable to medical care took part in this study, they were on accidental spine scoliosis (From $15^{\circ}to35^{\circ}$). They were consisted of Group I(10 chest-bend) and Group II (10 dual-bend). The results were follows: 1. It showed the average difference in height by 1.37cm, 3.14cm in comparison between before and after TLSO, before and after one year and they were also statistically available(p < .05). 2. It showed the average difference in Cobb angle of a chest and waist by ($-10.95^{\circ},-8.50^{\circ}$), between before and right after TLSO. The results means that the Cobb angle of the chest and weist at right after TLSO was largely decreased, and it was also statistically available(p < .05). 3. It showed the difference in Cobb angle of the chest waist by $-9.50^{\circ},-7.35^{\circ} $ between before and one year after TLSO. It means that the Cobb angle of the chest and waist at the one year after TLSO was largely decreased, and it was also statistically available(p < .05). 4. It showed the difference in Cobb angle of the chest and waist by $2.34^{\circ},2.15^{\circ} $ between the right after and the one year after. TLSO, but the change of Cobb angle of the chest was regularly constant by a little increased, and it was also statistically available(p < .05). 5. In the measurement of the change of Cobb angle of the chest and waist according to the taking time on TLSO, it showed the slightest change in 10 people on TLSO for 23 hours by $13.30^{\circ},11.20^{\circ}$ , the change in 6 people on TLSO for 16 hours by $14.75^{\circ},12.67^{\circ}$, the change in 4 people on TLSO for 8 hours by $16.83^{\circ},14.00^{\circ} $ in this order. It means that the longer time on TLSO was to be the smaller the Cobb angle of the chest and waist, but it was not statistically available.

• PNF and Movement
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• v.18 no.1
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• pp.65-75
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• 2020

Purpose: The purpose of this study was to investigate the differences in muscle thickness and ground reaction force of the vastus medialis oblique and vastus lateral oblique muscles during squats at ankle angles of toe 0°, toe in 10°, and toe out 10°. Methods: In this study, 9 male and 17 female students in their 20s participated in a randomized controlled trial and were compared according to the ankle angles of toe 0°, toe in 10°, and toe out 10°. To determine the reliability and measurement of muscle thickness according to ankle angle using ultrasound equipment and muscle thickness, the participants' ankle angles-toe 0°, toe in 10°, and toe out 10°-were measured three times at the vastus medialis oblique and vastus lateralis oblique muscles during squats. At the same time, the maximum vertical ground reaction force was measured with a force plate. A total of three measurements were taken and averaged, and two minutes of squat movements were assessed between ankle angles to prevent target action. Results: The results of this study illustrated that the reliability of the vastus medialis oblique muscles and vastus lateralis oblique muscles in ankle angle was high. The difference in muscle thickness was significantly greater in comparing the toe out 10° angle with the toe 0° angle than between toe in 10° and toe out 10° in vastus medialis oblique and vastus lateralis oblique (p < 0.05). There was no statistically significant difference between the ankle angle of toe 0° and toe in 10° (p > 0.05). The maximum vertical ground reaction force was significantly greater at toe out 10° than at the ankle angle of toe 0° and toe out 10° and between toe in 10° and toe out 10° (p < 0.05). There was no statistically significant difference in the comparison between toe 0° and toe in 10° (p > 0.05). Conclusion: Squatting at an ankle angle of toe out 10° increases the dorsi flexion; thus, the stability of the ankle and the thickness of both oblique muscles increased to perform more effective squats. In addition, as the base of support widens, it is thought that the stability of the posture increases so that squat training can be performed safely.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.2
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• pp.41-48
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• 2018

The quantitative interfacial adhesion energy measurement method of copper redistribution layer and WPR dielectric interface were investigated using $90^{\circ}$ peel test, 4-point bending test, double cantilever beam (DCB) measurement for FOWLP Applications. Measured interfacial adhesion energy values of all three methods were higher than $5J/m^2$, which is considered as a minimum criterion for reliable Cu/low-k integration with CMP processes without delamination. Measured energy values increase with increasing phase angle, that is, in order of DCB, 4-point bending test, and $90^{\circ}$ peel test due to increasing roughness-related shielding and plastic energy dissipation effects, which match well interfacial fracture mechanics theory. Considering adhesion specimen preparation process, phase angle, measurement accuracy and bonding energy levels, both DCB and 4-point bending test methods are recommended for quantitative adhesion energy measurement of RDL interface depending on the real application situations.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.1
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• pp.84-92
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• 1995

The methods by turning circle test and maneuvering indices have been used to study and evaluate the maneuverability of a ship. However recently many studies utilizing the GPS are made on the measurement of the turning circle and in the fishery and hydrographic survey. In this paper, the author carried out the turning circle test using the differential GPS and dumb card together, and compared the data measured by them and analyzed the accuracies of them to obtain the utility basic ones on the measurement of the turning circle by the DGPS. The main results area s follows : 1) To check the accuracies of the GPS, the circling experiments of 50m radius by the DGPS were made on the ground. The accuracies of turning circle measured by the DGPS were found to be very high as the errors of 1.5m. 2) the turning circle by the DGPS could be measured very accurately, by the seed, rudder angle, starboard and port respectively. 3) The turning circle measured by the dumb card was found to be measured accurately as much as the DGPS, when using large rudder angle, the turning circle was large, the turning circle by the dumb car could not be measured accurately on account of large error of bearing of compass. 4) The tactical diameters by the DGPS in case of the rudder angle 35。~5。, were found to be 2.6。15.0 times the Lpp of S.T HAELIM-3 at her slow speed 2.8~16.6 times her Lpp at her half speed, 3.1~17.4 times her Lpp at her full speed. The tactical diameter by the dumb card was found to be 2.4~9.5 times, 2.6~9.6 times, 3.2~12.2 times her Lpp respectively, in the above case and speed.

• Journal of Periodontal and Implant Science
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• v.34 no.2
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• pp.281-292
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• 2004

Periodontal defects of the furcation are characterized by several inherent anatomic factors that can make successful periodontal therapy difficult and results unpredictable. The severity and rate of occurrence of periodontal disease are directly related to the location of the furcation relative to the cementa-enamel junction and anatomical form of the root by limiting the accessibility and effectiveness of the periodontal instrumentation. This study investigated the reliability and accuracy of panoramic radiograph diagnoses of the periodontal state of mandibular molars, particularly regarding the diagnosis of furcation area periodontal defects, treatment planning, and prognosis prediction. This study examined a total of 110 teeth belonging to 33 subjects (19 male, 14 female) presenting with incipient to moderate periodontitis 4-7mmpocket depth. The alveolar bone level, length and width of the root trunk, and root separation angle were measured using the panoramic radiograph and compared to the results taken directly by retracting a full-thickness flap. The results of the study are as follows: 1. Data regarding the alveolar bone level of the mandibular first molar showed that the directly taken surgical measurements resulted in $5.1{\pm}0.9mm$ that was slightly deeper than the corresponding panoramic measurement resulted in $4.8{\pm}0.8mm$, but these differences were statistically insignificant (p>0.05). 2. The data of the directly taken surgical measurement of the mandibular second molar $(5.1{\pm}1.1mm)$ was slightly deeper than the corresponding panoramic measurement $(4.7{\pm}1.2mm)$, but these differences were statistically insignificant (p>0.05). 3. The measured values of the length and width of the mandibular first molar root trunks were determined to be $4.1{\pm}0.6mm$ and $7.3{\pm}0.9mm$, respectively, while the values of the mandibular second molar root trunks were determined to be $4.6{\pm}1.3mm$ and $7.6{\pm}0.9mm$ respectively. The differences between these values were found to be statistically significant (p<0.01). 4. The measured values of the root separation angle showed that the mandibular first molars averaged $34.5{\pm}4.4^{\circ}$, while the mandibular second molars averaged $23.0{\pm}10.0^{\circ}$. The differences between these values were found to be statistically significant (p<0.01).

• Journal of Oral Medicine and Pain
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• v.21 no.2
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• pp.305-315
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• 1996

This study was performed to investigate the changes of head posture according to natural standing or sitting posture. Twenty seven healthy dental students without any signs and symptoms of temporomandibular disorders participated in this study. Cervical resting posture (CRP) of the head in sagittal plane was measured by Cervical-Range-of-Motion $^\textregistered$(CROM, U.S.A.) and lateral cephalograph was taken in natural posture. The items related to angle in cephalograph were the angles of cranial and cervical inclination to true vertical line(VER/NSL, VER/AML), the angles of cervical inclination to nasion-sella line(CVT/NSL, OPT/NSL), the angles of comical inclination to horizontal line(CVT/HOR, OPT/HOR), the angle of cervical lordosis(CVT/OPT). The items related to line measurement were the distance from subocciput to Cl(Dl), Cl to C2(D2), C2 to C3(D3), C3 to C4(D4), the upper(PNS to posterior pharyngeal wall) and the lower(tongue base to posterior pharyngeal wall) pharyngeal space, the distance from nation to mention(Na-Me), and the radius of comical curvature from the first comical vertebra(Cl ) to the fifth cervical vertebra(C5). The data were analyzed with SAS/STAT program. The obtained results were as follows : 1. Most items related to angular measurement showed significant difference between in standing and sitting posture. The angles of CRP, CVT/NSL, OPT/NSL, CVT/HOR, OPT/HOR, and CVT/OPT were high in sitting posture, but the angles of VER/NSL, VER/NSL were low in sitting posture. 2. In vertebral distance, only the distance between C3 and C4 was differed by the posture, which decreased in sitting posture. In sitting posture, the distance from nasion to menton(Na-Me) was longer, but the radius was shorter than in standing posture. 3. Correlationship in angular measurements was almost same in both postures. Ceervical resting posture(CRP) was correlated with VER/NSL, VER\ulcornerNSL was correlated with CRP, CVT/NSL, and OPT/NSL, VER/AML was correlated with CVT/HOR, OPT/HOR, CVT/OPT, and the angle of cervical lordosis(CVT/OPT) was correlated with the radius. 4. Correlationship in linear measurement was observed only in among D3, D4, and radius. And the Na-Me was not correlated with any other items. From this results, The author concluded that the head posture in sitting was mote backward extended than in standing.