• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.54-62
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• 2016

The most efficient system for converting heat to electricity, AMTEC (Alkali Metal Thermal-to-Electric Convertor), is a device that directly converts heat energy to electricity using an alkali metal (sodium) as the working fluid. The AMTEC consists of a low pressure chamber, high pressure chamber, BASE (Beta-Alumina Solid Electrolyte), and artery wick. The main heat loss of the AMTEC system occurs in the low pressure chamber. A high power generation rate is thought to be obtainable by using a high temperature in the BASE. Therefore, to reduce the radiation heat loss, 6 types of radiation shields were examined to reduce the radiative heat loss in the low pressure chamber. The power generation rate of the AMTEC varied depending on the shape of the radiation shield. CFD (Computational Fluid Dynamics) analyses were carried out to optimize the shape of the radiation shield. As a result, the optimum radiation shield was found to consist of a curvature formed at the vertical point, in which case the dimensionless temperature (condenser temperature/BASE temperature) is approximately 0.665 and the maximum power generated is calculated to be 17.69W. Increasing the distance beween the BASE and condenser leads to an increase in the power generated, and the power generated with the longest distance was 17.58 W. The shields with multiple holes and multiple horizontal layers showed power reduction rates of 0.91 W and 2.06 W, respectively.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.1-19
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• 2008

This research is to analyze the force on landing 3 Type of Halfpipe Curves(Ellipse, Circle, Brachistochrone) based on the mechanical calculation of normal force on a sloping surface. Jumping off a platform on a bard horizontal surface, the flexing of the legs, the softness of the snow, the angle of the landing surface, initial velocity and the forward motion of the snowboarder can contribute to reducing the force on landing. But halfpipe is significantly determined by the curvature of surface. It is definitely verified that the Brachistochrone curve is more safety than others. However currently using the Ellipse curve is mostly safe too. If we consider the efficiency of construction, we can easily think there is no use of another curves except normal ellipse curved halfpipe. It would better that geometrically verity curved halfpipe should be designed for improving fluent skills to snowboarders. This methode of research can be a model of scientifical research on sports safety how can sportsman reduce critical injury by designing optimal halfpipe facilities and manual.

• The korean journal of orthodontics
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• v.28 no.4 s.69
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• pp.499-515
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• 1998

The purpose of this study was to examine the associations of head posture the position of the tongue or the hyoid bone to craniofacial structure. Cephalograms taken in Natural head position(NHP) of 90 dental students (50 in male, 40 in female, 20 to 30 years in age) were traced and measured using the extracranial true horizontal and vertical lines. The obtained results were as follows; 1. There was no sex difference in head posture, but the hyoid bone was placed anteroinferiorly in male more than in female and anteroinferior inclination of the hyoid bone showed greatly in male. 2. The more inclined was the cervical column, the less prognathic was the face in natural head posture, and the larger cervical curvature, the more vertical pattern of the face. 3. The less small showed craniocervical angulation, the more anteriorly placed was the hyoid bone to the cranial base, and there was no significantly association between craniocervical angulation and the vertical position of the hyoid bone. 4. The more prognathic was the mandible, the more anteriorly placed was the hyoid bone, and there was slightly association between the craniofacial morphology and the vertical position of the hyoid bone.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.325-334
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• 2010

In this study, an unbraced five-story steel-framed structure was designed in accordance with KBC2005 to understand the features of structural behavior for the arrangement of semi-rigid connections. A pushover analysis of the structural models was performed, wherein all the connections were idealized as fully rigid and semi-rigid. Additionally, horizontal and vertical arrangements of the semi-rigid connection were adopted for the models. A fiber model was utilized for the moment-curvature relationship of the steel beam and the column, and a three-parameter power model was adopted for the moment-rotation angle of the semi-rigid connection. The top displacement, base-shear force, required ductility for the connection, sequence of the plastic hinge, and design factors such as the overstrength factor, ductility factor, and response modification coefficient were investigated using the pushover analysis of a 2D structure subjected to the equivalent static lateral force of KBC2005. The partial arrangement of the semi-rigid connection was found to have secured higher strength and lateral stiffness than that of the A-Semi frame, and greater ductility than the A-Rigid frame. The TSD connection was found suitable for use for economy and safety in the sample structure.

• 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.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.4
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• pp.1-10
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• 2023

In the seismic design of structures, seismic forces are calculated based on structural models and analysis. In order to accurately address the dynamic characteristics of the actual structure in the structural model, calibration based on actual measurements is required. In this study, a 4-story frame test specimen was manufactured to simulate frame building, accelerometers were attached at each floor, and 1-axis shaking table test was performed. The natural period of the specimen was similar to that of the actual 4 story frame building, and the columns were designed to behave with double-curvature having the infinite stiffness of the horizontal members. To investigate the effects seismic waves characteristics, historical and artificial excitations with various frequencies and acceleration magnitudes were applied. The natural frequencies, damping ratios, and mode shapes were obtained using frequency response functions obtained from dynamic response signals, and the mode vector deviations according to the input seismic waves were verified using the Mode assurance criterion (MAC). In addition, the damping ratios obtained from the vibration tests were applied to the structural model, and the method with refined dynamic characteristics was validated by comparing the analysis results with the experimental data.

• Journal of the Daesoon Academy of Sciences
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• v.41
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• pp.133-178
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• 2022

This study investigates if four propitious sites (四明堂, sa myeongdang) identified in Daesoon Jinrihoe's The Canonical Scripture correspond with the orthodox descriptions of dragon, energy hub, sand, and water (龍穴砂水, yong hyeol sa su) which are held by Fengshui as conditions necessary for that specific designation. In this study, these conditions, based on the shape of the site-formations, were observed via through on-site surveys and the application of the theories presented by traditional books on Fengshui. First, the dragon veins (龍脈, yongmaek) of the energy hub of the Five Immortals Playing Baduk (五仙圍碁穴 oseonwigi- hyeol) on Mount Hoemun in Sunchang consists of solid soil, is like a spiderweb, rises and lays prone, winds in every direction, and looks almost disconnected while actually remaining connected. Second, the Fengshui characteristics of the energy hub of Worship Held by Buddhist Monks from Abroad (胡僧禮佛穴, hoseungyebul- hyeol) on Mount Seungdal in Muan is that the branching feet (枝脚 jigak) support the mountain range by forming a valley to the left and right of the dragon veins that stretch from the peak of Mount Seungdal. Also, the direction-changing helm (橈棹 yodo) supports the mountain range solidly can be said to be well-developed. It is likewise noted that there is an excellent change in dragon veins in that exhibit curvature that spans being high, low, rising, and lying. This makes it appear as though the dragon is wriggling back and forth. Third, the state of the energy hub of Celestial Maidens Weaving Silk (仙女織錦穴, seonnyojikgeum-hyeol) on Sonryong Ridge in Jangseong County demonstrates overall harmony between mountain and water as it is near Mount Ju and Mount An and has a solid water outlet to which it is tightly fastened such that its energy does not leak out. Meanwhile, the positioning of its blue dragon of the east, red phoenix of the south, white tiger of the west, and black tortoise of the north is so intimate that its long flow can be said to be spinning. The Songryong Ridge area where energy hub was formed between soil and bedrock is the right land for a great favored location as it corresponds with Fengshui logic in an exemplary manner. Fourth, the Fengshui characteristics of the energy hub of Subjects Receiving the Imperial Command (群臣奉詔穴, gunshinbongjo-hyeol) at Baerye-jeon Field in Taein can be described as embracing the village snuggly as it centers around Mount Wangja, and its blue dragon and white tiger respond to each other. Additionally, a clear distinction between host and guest is noticeable in the positions of Mount Ju and Mount An. The flowing body of water in front of the village wraps around that village as a Horizontal Water Formation (橫水局, hoengsuguk), and vigorous vapor from the earth draws breath as the yin-yang energy of the landscape courses through the earth. As dragon veins, the range of the mountain, are like the blood vessels within the human body and the dragon is compared to the limbs, the energy hub of Subjects Receiving the Imperial Command at Baerye-jeon Field in Taein can be identified as a favored location that was formed directly by the sky and earth.