• Journal of Digital Convergence
• /
• v.13 no.8
• /
• pp.465-472
• /
• 2015

The virtual reality technology is currently used classifying functional types such as the observation operation type, the experimental activity type, the learning information type, the field problem-solving type, and other different types, based on the media's characteristics implementing 3D form of multi-sensory information. Using Virtual Reality, the restoration of the 'Doksu Palace' has been grafted onto J. Keller's ARCS model, suggesting a field restoration concept that reenacts the lives of the people that had been in the field with the cultural heritage and history based on a scenario based scene direction. This paper also summarizes 3 different types of implementation of the field restoration assorting multi-scene direction. Certain limitations exist, due to the fact that a completed prototype hasn't been suggested and that a detailed notion of the housing and 3D audio connection has been omitted.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.28 no.1
• /
• pp.35-48
• /
• 1995

To develop the optimal design method for the longline type scallop culturing facilities in the open sea numerical calculations and hydraulic model experiments are carried out for the stability and function optimization. Using the results for the motion and tension of the facilities, stable design concepts and effects of motion control system by vertical anchor and resistance discs art discussed. The results of this study that can be applied to the design are as follows: 1) Total external forces by design wave $(H_{1/3}\;=\;6,7\;m,\;T_{1/3}\;=\;12sec)$ at the coastal waters of Jumunjin for unit facility (one main line) are estimated to 5-20 tons, and required anchor weights are 10-40 tons in the case of 2-point mooring system. Though the present facilities are stable to steady currents, but is unstable to the extreme wave condition of return period of 10 years. 2) The dimensions and depth of array systems must be designed considering the ecological environments as well as the physical characteristics including the mooring and holding forces that are proportional to the length and relative depth of main line to wave length, and the number of buoys and nets. 3) Oscillation of the facility is influenced by water particle motion and the weight of hanging net, and is excited at both edge, especially at the lee side. To reduce the motion of the nets, the vertical anchoring system and the resistence disc method are recommended by the experimental results, 4) The damage of rope near the anchor by abrasion should be prevented using the ring-type connection parts or anchor chains.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.9
• /
• pp.70-77
• /
• 2006

We have fabricated an integrated three-phase flux-lock type SFCL, which consists of an YBCO($YB_a2Cu_3O_7$) thin film and a flux-lock reactor wound around an iron core of each phase. In order to apply the SFCL in a real power system, fault analyses for the three-phase system are essential. The short-circuit currents were effectively limited by adjusting the numbers of winding of each secondary coil and their winding directions. The flux flow generated in the iron core cancelled out under the normal operation due to the parallel connection between primary and secondary windings. However, the flux-lock type SFCL with same iron core was operated just after the fault due to the flux generating in the iron core. To analyze the current limiting characteristics, the additive polarity winding was compared with the subtractive one in the flux lock reactor. Whenever a single line-to-ground fault occurred in any phase, the peak value of the line current of the fault phase in the additive polarity winding increased up to about 12.87 times during the first-half cycle. On the other hand, the peak value in the subtractive polarity winding increased up to about 34.07 times under the same conditions. This is because the current flow between the primary and the secondary windings changed to additive or subtractive status according to the winding direction. We confirmed that the current limiting behavior in the additive polarity winding was more effective for a single-line-to-ground fault

• Journal of Power Electronics
• /
• v.15 no.6
• /
• pp.1609-1618
• /
• 2015

DC microgrids are considered as prospective systems because of their easy connection of distributed energy resources (DERs) and electric vehicles (EVs), reduction of conversion loss between dc output sources and loads, lack of reactive power issues, etc. These features make them very suitable for future industrial and commercial buildings' power systems. In addition, the bipolar-type dc system structure is more popular, because it provides two voltage levels for different power converters and loads. To keep voltage balanced in such a dc system, a bidirectional dual buck-boost voltage balancer with direct coupling is introduced based on P-cell and N-cell concepts. This results in greatly enhanced system reliability thanks to no shoot-through problems and lower switching losses with the help of power MOSFETs. In order to increase system efficiency and reliability, a novel burst-mode control strategy is proposed for the dual buck-boost voltage balancer. The basic operating principle, the current relations, and a small-signal model of the voltage balancer are analyzed under the burst-mode control scheme in detail. Finally, simulation experiments are performed and a laboratory unit with a 5kW unbalanced ability is constructed to verify the viability of the bidirectional dual buck-boost voltage balancer under the proposed burst-mode control scheme in low-voltage bipolar-type dc microgrids.

• Journal of Korean Society of Steel Construction
• /
• v.27 no.1
• /
• pp.53-61
• /
• 2015

The tension type joint is a mechanically very efficient connection method, as it directly uses the load capacity of base metal or high tension bolt, the reduction of the number of drilling hole and fastening and the fatigue resistance. It is applied to the joint of girder and cross beam, horizontal joints of towers, beam to column joints, the secondary member joints of deck floor ends, and brackets. In this paper, static load tests for the T-type tension joint were conducted to investigate the structural behavior of the joint. The parameters were bolt diameter, flange thickness, and the reduction of clamping force of the joint. The failure modes and load capacity of joints and the effects of flange thickness, bolt diameter and clamping force were investigated.

• 한국태양에너지학회:학술대회논문집
• /
• 2008.04a
• /
• pp.43-48
• /
• 2008

Through simulations and field experiment on A.C. parallel operation of both Utility Interactive Photovoltaic System and Diesel Engine Revolving Field Type Synchronous Generator, following factors have been found. First, the inverter should be operated in three modes of frequency(mode.1: ${\pm}$0.3Hz, mode.2: ${\pm}$1Hz, mode.3: ${\pm}$2Hz) as default, considering properties of operating Synchronous Generator. Second, as a result of supplying 13.5kW of residual power, it has been found that Synchronous Generator takes the power input only as reactive power, because it was electrically stable with frequency of 60.14Hz and high voltage of 222.3V even when power factor was -0.94. Besides, it was mechanically stable, too, because the quake, noise, and temperature of Synchronous Generator in this case were 7.5mm/s, 97dB, and $6^{\circ}C$ respectively, which were lower than normal load connection of 145.6kW; 11.03mm/s. Thus, load share of Revolving Field Type Synchronous Generator reduces according to the supply of Photovoltaic System to the load power. In this experiment, 200kW of Synchronous Generator and 40kW of Photovoltaic System were operated in parallel. The load share was 20% in maximum. and 11.1lit/hr of fuel was saved.

• Journal of Korean Society of Steel Construction
• /
• v.28 no.6
• /
• pp.427-438
• /
• 2016

This study is experimental research for the effect of gap at the end plate on the performance of extended end-plate type splice. For this research, simple beam type specimens by using extended end-plate type splice are planned. Main variables are the initial gap between end-plates, the installation of finger shim plate before the installation of high tension bolts, the final gap between end-plates, and the installation of finger shim plate after the installation of high tension bolts. The static loading tests results show that the maximum bending strength of splice is not dependent on the gap, but the vertical displacement, initial stiffness and elastic stiffness are affected by the gap. In addition to that, the possibility of brittle fracture is increased when the torque of high tension bolt is used to control the gap. Thus, careful consideration is needed in this case.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.46 no.2
• /
• pp.133-142
• /
• 2020

Objectives: In this study, we determined the incidence and pattern of screw loosening in patients who received dental implants. Materials and Methods: Patients who received implants between January 2008 and October 2013 and completed their prosthetic rehabilitation were evaluated for the incidence, frequency, and onset of screw loosening using dental charts and radiographs. The association between each factor and screw loosening was analyzed using the chi-square test and a multivariate analysis with binary logistic regression models (P<0.05). Results: Total 1,928 implants were placed in 837 patients (448 males, 389 females), whose follow-up period after loading varied from 0.25 to 70 months (mean period, 31.5 months). Screw loosening occurred in 7.2% of implants. Most cases occurred less than six months after loading. Among those, 22.3% experienced recurrent screw loosening. Screw loosening was most common in the molar region (8.5%) and frequently associated with an implant diameter of ≥5 mm (14.2%). External implant-abutment connections (8.9%) and screw-retained implant prostheses (10.1%) showed higher incidence of problems than internal implant-abutment connections and cement-retained implants, respectively. Screw loosening was most common in implant prostheses with single crowns (14.0%). Conclusion: Within the limits of the current study, we conclude that the incidence of screw loosening differs significantly according to the position of implant placement, the type of implant and manufacturer, implant diameter, the type of implant-abutment connection, the type of retention in the implant prosthesis, and the type of implant prosthesis.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.23 no.2
• /
• pp.301-307
• /
• 2009

In korean society, the chronic life style diseases are increasing. It is caused by the approach of the aged society and the highly increasing income. Accordingly the preventive side of the health promotion and management is very important. In the oriental medicine, the general disease pre-estimate and the management program are necessary. On this point, the sign forecast is very significant in connection with the disease pre-estimate in the preventive disease management side. The sign forecast according to the human shape type diagnosis is mainly the sign of the super-early stage, The difference of the shape type has the difference of the special affinity about the disease. Accordingly we can find the sign forecast from the latent disease in the early stage. In NAE-GYEONG(內經), the theory of "five body form's type" can be pre-estimated the latent tendency and the clue of the disease and the growing tendency of disease in relation to the Differentiation of Syndrome, In the disease pre-estimate side, the graspe and management of the sign forecast from the latent disease will be the part of the new development.

• Korean Journal of Human Ecology
• /
• v.18 no.4
• /
• pp.971-984
• /
• 2009

The purpose of this study was to analyse the relations among the residents' characteristics, the policy of the facility, and the physical characteristics of activity areas, and to understand the elements for the lively use of activity areas in the elderly nursing facilities. The results of the study are as follows: First, there was a relationship between the characteristics of semi-public activity areas and the residents' management-control policy. The facilities having semi-public areas of living room type showed more flexibility in time and place and more respects for the residents. Second, the activity areas of connection type were much more used than the compartment type, especially in the facilities having more residents incapable of walking. On the other hand, the facilities having high control for the residents showed high using rate in public activity areas, and all those did not have semi-public areas or showed low using rate in there. Third, in the analysis of the relationship between the physical characteristics and the using rate of activity areas, the public activity areas having compartment type in the spatial composition and hall as a form were likely to have multiple usages. On the whole, the various form of activity areas, the area per residents, openness, accessibility and centrality were having interactions each other for high using rate in activity areas. Especially, many stimulations and the furniture arrangements that were good for the residents' interactions had a function of compensation for the poor physical characteristics of activity areas. This study investigated only the using rates to understand the lively use of the space. For the future study, it is suggested that the detail using behavior of the residents should be examined to understand the influential elements.