• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.713-721
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• 2022

In order to use the LED video wall in the broadcasting studio, there are a few things to be aware of. First, since the pixels are closely arranged, a moire phenomenon may occur due to a short arrangement period, and second, the distance between pixels (pixel pitch) may be recorded on the image sensor of the broadcasting camera. When moire occurs or pixel pitch is observed, viewers feel uncomfortable. Moire effect can be reduced by adjusting the shooting distance or angle of the camera, but in order to prevent the pixel pitch from being recorded on the image sensor, secure a sufficient distance between the LED video wall and camera. even when the distance secured, the zoom lens used in the broadcasting studio must be operated by appropriately changing the magnification. If the focal length is changed by changing the magnification to obtain a desired angle of view, the pixel pitch may be unintentionally recorded. In this study we propose the range that the pixel pitch is not observed while changing the magnification ratio of the zoom lens when the distance from the video wall is sufficiently secured. The content was played back on the LED video wall and the LED video wall was recorded on the server using an HD camera equipped with a B4 mount zoom lens

• Journal of the Korean Arthroscopy Society
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• v.6 no.2
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• pp.101-108
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• 2002

Purpose: To evaluate the clinical results of anterior cruciate ligament (ACL) reconstruction and to know the results of physeal injury by transphyseal tunnel in adolescents who had remaining growth potential. Materials and Methods : This study involved 12 patients under 19 years old out of 445 patients, who underwent ACL reconstruction between 1993 and 2001. The mean age at the time of operation was 15.9 $(13.1\~16.9)$ years and fellow-up period was 45.1 $(24\~120.6)$ months in avrarge. Autologous quadrupled hamstring tendon was used as graft in 11 cases and bone-patellar tendon-bone in 1 case. Clinical results were evaluated by Lysholm Knee Scoring Scale, range of motion and return to preinjury sports activities. Radiologic results were evaluated by $Telos^{\circledR}$ device. Bone maturity were analyzed by chronological age, standing height and the width of growth plate in AP and lateral view of knee joint at preoperatively. The growth disturbances were evaluated by measuring femorotibial angle, anatomical and mechanical lateral distal femoral angle, mechanical medial proximal tibial angle and leg length and by comparing those of uninjured site in last follow-up teleoroentgenogram. Results : The mean Lysholm Knee score was 51 $(25\~63)$points preoperatively and 98 $(94\~100)$ points at last follow up. The mean anterior displacement of the tibia by using $Telos^{\circledR}$ device was improved from 13.5 $(6\~27)$ mm to 2.9 $(1\~4)$ mm and there were no significant instabilities of the knee in all cases. There were no leg length discrepancies over 1 cm and no statistically significant abnormal alignment of the knee joint in all cases. Conclusion: ACL reconstruction using transphyseal tunnel for restoring stability and knee function is assumed as a good mettled of treatment without significant leg length discrepancy and abnormal alignment of the knee joint.

• Korean Journal of Remote Sensing
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• v.21 no.6
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• pp.445-456
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• 2005

The land surface parameters should be determined with sufficient accuracy, because these play an important role in climate change near the ground. As the surface reflectance presents strong anisotropy, off-nadir viewing results a strong dependency of observations on the Sun - target - sensor geometry. They contribute to the random noise which is produced by surface angular effects. The principal objective of the study is to provide a database of accurate surface reflectance eliminated the angular effects from MODIS 250m reflective channel data over Korea. The MODIS (Moderate Resolution Imaging Spectroradiometer) sensor has provided visible and near infrared channel reflectance at 250m resolution on a daily basis. The successive analytic processing steps were firstly performed on a per-pixel basis to remove cloudy pixels. And for the geometric distortion, the correction process were performed by the nearest neighbor resampling using 2nd-order polynomial obtained from the geolocation information of MODIS Data set. In order to correct the surface anisotropy effects, this paper attempted the semiempirical kernel-driven Bi- directional Reflectance Distribution Function(BRDF) model. The algorithm yields an inversion of the kernel-driven model to the angular components, such as viewing zenith angle, solar zenith angle, viewing azimuth angle, solar azimuth angle from reflectance observed by satellite. First we consider sets of the model observations comprised with a 31-day period to perform the BRDF model. In the next step, Nadir view reflectance normalization is carried out through the modification of the angular components, separated by BRDF model for each spectral band and each pixel. Modeled reflectance values show a good agreement with measured reflectance values and their RMSE(Root Mean Square Error) was totally about 0.01(maximum=0.03). Finally, we provide a normalized surface reflectance database consisted of 36 images for 2001 over Korea.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.442-458
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• 2014

Wave induced vibrations increase the fatigue and extreme loading, but this is normally neglected in design. The industry view on this is changing. Wave induced vibrations are often divided into springing and whipping, and their relative contribution to fatigue and extreme loading varies depending on ship design. When it comes to displacement vessels, the contribution from whipping on fatigue and extreme loading is particularly high for certain container vessels. A large modern design container vessel with high bow flare angle and high service speed has been considered. The container vessel was equipped with a hull monitoring system from a recognized supplier of HMON systems. The vessel has been operating between Asia and Europe for a few years and valuable data has been collected. Also model tests have been carried out of this vessel to investigate fatigue and extreme loading, but model tests are often limited to head seas. For the full scale measurements, the correlation between stress data and wind data has been investigated. The wave and vibration damage are shown versus heading and Beaufort strength to indicate general trends. The wind data has also been compared to North Atlantic design environment. Even though it has been shown that the encountered wind data has been much less severe than in North Atlantic, the extreme loading defined by IACS URS11 is significantly exceeded when whipping is included. If whipping may contribute to collapse, then proper seamanship may be useful in order to limit the extreme loading. The vibration damage is also observed to be high from head to beam seas, and even present in stern seas, but fatigue damage in general is low on this East Asia to Europe trade.

• Polymer(Korea)
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• v.36 no.6
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• pp.761-767
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• 2012

The polycarbonate (PC)-based optical diffusers for direct-lit LED backlight unit were prepared by using extrusion compounding followed by compression molding process. The application of inorganic porous silica particles as a diffusing agent in addition to conventional poly(methyl methacrylate) (PMMA) beads was attempted, and the optical, thermal, and mechanical properties of the prepared diffusers were investigated. The morphological observations revealed that the diffusing agents could be uniformly dispersed in the PC matrix without agglomeration by high shear stress generated during extrusion process. The incorporation of the porous silica particles mixed with PMMA beads remarkably enhanced the luminance uniformity with respect to both location and view angle for the diffuser, while minimizing the reduction in the absolute luminance, as compared with the diffuser containing only PMMA beads. In addition, thermal and mechanical properties of the diffusers were shown to be improved upon addition of the porous silica particles.

• Nutrition Research and Practice
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• v.14 no.6
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• pp.667-678
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• 2020

BACKGROUND/OBJECTIVES: This study aimed to improve portion size estimation aids (PSEAs) used in the nutrition survey of the Korea National Health and Nutrition Examination Survey (KNHANES) and validate the accuracy and precision of the newly developed aids. SUBJECTS/METHODS: We conducted intensive interviews with survey experts in KNHANES and consulted with experts to collect opinions about improvement of PSEAs. Based on the results of the interviews, 5 types of PSEAs (rice bowl, earthen pots, mounds, measuring spoons, and thickness sticks) were newly developed using 3-dimensional (3D) modeling or modification of color or shape. Validation tests were conducted with 96 adults 20 years old or older. For the rice bowl and earthen pots, the participants were asked to select the more similar PSEA in size after being shown the real dishes. For the mounds, measuring spoons, and thickness sticks, the participants were presented with actual plates of food and asked to estimate the given portion sizes using the given PSEAs. RESULTS: The improved 2-dimensional (2D) picture aid for the rice bowl reflecting the size distortion by angle of view using 3D modeling was perceived more closely to the actual size than the current 2D picture (P < 0.001). The change of the color of 2D pictures and 3D models, the change of shape of the measuring spoons, and the 3-dimensionalization of the 2D mounds had no significant improvement in the subjects' perception. CONCLUSIONS: The currently used 2D PSEAs need to be fully redesigned using 3D modeling to improve subjects' perception. However, change of color or shape will not be necessary. For amorphous foods, it is suggested that more evaluation be performed before reaching a final conclusion in the use of PSEAs, or alternative ways to improve accuracy of estimation need to be explored.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.6
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• pp.68-76
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• 2011

We introduce a parallax barrier type autostereoscopic display in order to overcome the limited viewing angle of the conventional parallax barrier type displays. The proposed method adopts a special structure of double pairs of ITO that have a common TN-LC at the core of the conventional parallax barrier. Compared with the conventional parallax barrier type displays, the proposed display uses moving parallax barriers and eye tracking system to make stereoscopic view images adapted to the movement of viewer. We implemented a prototype of the proposed dual layer parallax barrier system, and verified that the proposed autostereoscopic display maintains seamless 3D views even when a viewer's head is moving.

• The korean journal of orthodontics
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• v.21 no.2 s.34
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• pp.325-340
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• 1991

There are evidences that occlusal splint therapy is critical to diagnose hidden akeleto-occlusal disharmonies in malocclusion patients and capable of enhancing stability after orthodontic treatment. In addition, evidences have implicated occlusal splint therapy in condylar positional changes during TMJ disorder treatment. In view of these evidences, this study was performed to investigate the effect of occlusal splint therapy on condylar positional changes in malocclusion patients and the possible clinical application of the occlusal splint as an additional orthodontic tool. For this study, 8 Angle's Class I malocclusion patients, who had centric occlusion-centric relation discrepancy within 1.0 mm and had no clinical symptoms of TMJ disorder, were selected as control group. And 22 malocclusion patients who had centric occlusion-centric relation discrepancy over 1.0 mm were selected and subdivided as Class I Malocclusion group, Class II div. 1 malocclusion group, Class II div. 2 malocclusion group, Open bite group, and Mandibular asymmetry group. For each subject the occlusal splint with mutually protected type of occlusal scheme was applied for 3 months. Condylar positions in centric relation and centric occlusion were measured using Panadent articulators and Panadent condylar position indicator (CPI) before and after occlusal splint therapy. On the basis of this study, the following conclusions might be drawn: 1, In control group, Class II div. 2 malocclusion group, and mandibular assymetry group, there were no significant differences in condylar positions before and after occlusal splint therapy. 2. In Class I malocclusion group, condyles were moved $0.27{\pm}0.45mm$ forward (p < 0.05) and $0.98{\pm}0.25mm$ upward (p < 0.01) after occlusal splint therapy. 3. In Class I malocclusion group, condyles were moved $0.24{\pm}0.21mm$ backward (p < 0.05) and $1.01{\pm}0.33mm$ upward (p < 0.01) after occlusal splint therapy. 4. In open bite group, condyles were moved $1.24{\pm}0.30mm$ upward (p < 0.01) after occlusal splint therapy. 5. In both control and experimental groups, there were no significant differences in lateral condylar positions before and after occlusal splint therapy.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.768-776
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• 1994

This paper describes computer-aided forging design for rib/web shaped parts. In manufacturing a part by means of forging process, the first step is to design the forging. This is done by modifying the given machined part geometry according to the requirements of the forging process. Traditionally, this is done by experienced forging designers using empirical forging design guidelines. Generally, it would be neither possible nor practical to develop a system which encompasses the design of all types of forgings. Accordingly, forging design can be simplified by considering critical two dimensional cross sections of the machined part geometry. This system is composed of three modules(process variable decision module, forging design module and redesign module) and each module is carried out in regular sequence. In the process variable decision module, first of all, the undercut is checked and modified, and then deep recesses and holes difficult to forge are eliminated. Also parting line, forging plane, forging plan view area, forging weight and maximum size(maximum height or width)are determined. In the forging design module, the magnitude of various allowances, draft angle, minimum web thickness, corner and fillet radius are determined and then geometry modification is performed. Finally, since the design rules and databases used in this system are based on parameters of the forging geometry, such as the trimmed forging plan area, forging weight, forging maxmum size, plausible estimates need to be made for these parameters. Therefore, in the re-design module, the design process is iterated until a satisfactory forging is obtained.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.123-130
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• 2007

This study is that the elderly female patients having low back pain(34 people) show a change of stabilization ratio after isotonic rehabilitation of 4 types(before exercise, after 4weeks, 8weeks, 12weeks). Under the cover of lumbar extension machine, isometric extension strength and stabilization ratio is measured and analyzed at some flexion angles(the degree of $0^{\circ}$, $12^{\circ}$, $24^{\circ}$, $36^{\circ}$, $48^{\circ}$, $60^{\circ}$, $72^{\circ}$). The conclusion is as follows. 1. The maximum lumbar extension strength at a range of 7 angles have an increase of 73.92% in case of 12weeks isotonic exercise(p<.001). 2. After 12weeks exercise, the lumbar flexion angle maximum extension strength, have an higher increase than 54% on the average at all angles(p<.001). These statistically show a meaningful increase of muscular strength. 3. After 12weeks isotonic exercise, the lumbar stabilization ratio have a decrease of 50.27% at a statistically meaningful level(p<.001). In case of 12weeks exercise comparing with 8weeks, the stabilization ratio decrease at the level of 1.85 versus 1. This figure is similar to that of a normal person. In view of this study, 12weeks exercise for the elderly female patients having low back pain has much influence on the change of lumbar stabilization ratio and this is the scientifically verified result of a long term exercise.