• The Journal of Korean Academy of Prosthodontics
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• v.61 no.4
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• pp.328-343
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• 2023

Recently, a method of fabricating an esthetic anterior fixed prosthesis by integrating data such as three-dimensional facial scan and jaw motion to form a virtual patient with dynamic occlusion has been introduced. This enables smooth communication with patients during the diagnosis process, improves the predictability of esthetic prosthetic treatment, and lowers the possibility of occlusal adjustment. In this case report, a virtual patient with dynamic occlusion was created in which the results of the treatment were simulated, and esthetic maxillary anterior fixed prosthesis was fabricated. With the aid of the virtual patient, the final restorations were satisfactory both in terms of esthetic and function.

• Journal of the Korean Society of Radiology
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• v.14 no.6
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• pp.841-848
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• 2020

In the field of radiation therapy using photon beams and electron beams, since each patient has a different sensitivity to radiation, skin side effects may occur even at the same dose. Therefore, if there is a risk of excessive dose to the skin, a dosimeter is attached to verify whether the correct dose is being investigated. However, since the skin dosimeter checks the attachment site visually by measuring a point dose, it is difficult to confirm an accurate dose distribution. As a result, the measurement and simulation errors of the material HgI₂ in the 6 MV photon beam were 3.73% and 5.24%, respectively, at the minimum thickness of 25 ㎛, and the material PbI₂ was 4.73% and 5.65%, respectively. On the other hand, as a result of the 6 MeV electron beam, the measurement and simulation errors of the material HgI₂ were 1.35% and 1.12%, respectively, at a minimum thickness of 25 ㎛, and the material PbI₂ showed relatively low attenuation error, 1.67% and 1.20%, respectively. Therefore, it was evaluated that the thickness of the photon beam within 25 ㎛ and the electron beam within 100 ㎛ is suitable to have a reduction rate error within 5%. This study presents a new research direction for a flexible dosimeter attached to the human body that is required in clinical practice and the construction conditions of a future skin dosimeter.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.3
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• pp.180-201
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• 2020

It has been widely known that the effect of diffracted waves at the tip of composite breakwater with finite length causes the change of standing wave height along the length of breakwater, the spatial change of wave pressure on caisson, and the occurrence of meandering damage on the different sliding distance in sequence. It is hard to deal with the spatial change of wave force on trunk of breakwater through the two-dimensional experiment and/or numerical analysis. In this study, two and three-dimensional numerical techniques with olaFlow model are used to approach the spatial change of wave force including the impulsive breaking wave pressure applied to trunk of breakwater, the effect of rear region, and the occurrence of diffracted waves at the tip of caisson located on the high crested rubble mound. In addition, it is thoroughly studied the mean wave height, mean horizontal velocity, and mean turbulent kinetic energy through the numerical analysis. In conclusion, it is confirmed that the larger wave pressure occurs at the front wall of caisson around the still water level than the original design conditions when it generates the shock-crushing wave pressure checked by not two-dimensional analysis, but three-dimensional analysis through the change of wave pressure applied to the caisson along the length of breakwater.

• The Journal of the Convergence on Culture Technology
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• v.7 no.3
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• pp.509-515
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• 2021

This study analyzes the efficient floor layout plan of classrooms for securing evacuation stability in school in case of fire by using the Pathfinder simulation program. Efficient evacuation methods and safety were evaluated by analyzing REST (Required Safe Egress Time) according to the allocation of personnel by floor targeting a high school 5-story building equipped with a ramp and stairs. The current status of personnel assignments exceeded the Required Safe Egress Time(RSET), resulting in a problem with evacuation safety. When students were placed on the 3rd, 4th, and 5th floors, the result was that the time exceeded RSET the most. When students were placed on the 1st, 2nd, and 3rd floors, the result was that they completed evacuation in the shortest time, less than RSET. In the current state, when evacuation was guided by designating an evacuation exit depending on the location, the result of shortening RSET was obtained. As a result, it is effective to put the students on the lower floors when placing students in high-rise school buildings in terms of evacuation safety, and in the preliminary training, it is required to designate evacuation exits so that they can use the nearest exit for each location in case of a fire. As a future research project, additional research is needed on the RSET when a fire occurs in a specific location according to whether the automatic fire door at that location is opened or closed.

• The korean journal of orthodontics
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• v.36 no.5
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• pp.339-348
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• 2006

Objective: With development of the skeletal anchorage system, orthodontic mini-implant (OMI) assisted on masse sliding retraction has become part of general orthodontic treatment. But compared to the emphasis on successful anchorage preparation, the control of anterior teeth axis has not been emphasized enough. Methods: A 3-D finite element Base model of maxillary dental arch and a Lingual tipping model with lingually inclined anterior teeth were constructed. To evaluate factors influencing the axis of anterior teeth when OMI was used as anchorage, models were simulated with 2 mm or 5 mm retraction hooks and/or by the addition of 4 mm of compensating curve (CC) on the main archwire. The stress distribution on the roots and a 25000 times enlarged axis graph were evaluated. Results: Intrusive component of retraction force directed postero-superiorly from the 2 mm height hook did not reduce the lingual tipping of anterior teeth. When hook height was increased to 5 mm, lateral incisor showed crown-labial and root-lingual torque and uncontrolled tipping of the canine was increased.4 mm of CC added to the main archwire also induced crown-labial and root-lingual torque of the lateral incisor but uncontrolled tipping of the canine was decreased. Lingual tipping model showed very similar results compared with the Base model. Conclusion: The results of this study showed that height of the hook and compensating curve on the main archwire can influence the axis of anterior teeth. These data can be used as guidelines for clinical application.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1A
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• pp.26-34
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• 2002

Mobile telecommunication systems such as IS-95 and IMT-2000 employ frame based communication using frames up to 20 msec in length and the receiving end has to store the whole frome before it is being processed. The size of the frame buffer ofter dominates those of the processing unit such as soft decision Viterbi decoder. The frame buffer for IMT-2000, for example, has to be increased 80 times as large as that of IS-95. One of the parameters deciding the number of bits in a frame will be obviously the number of bits in soft quantization. Start after striking space key 2 times. This paper has studied a new aspect of offset and quantization step size on BER performance and proposes a new 3-bit soft quantization algorithm which shows similar performance as that of 4-bit soft decision Viterbi receiver. The optimal offset values and step sizes for the other practical quantization levels ---16, 8, 4, 2--- have also been found. In addition, a new optimal symbol metric table has been devised which takes the accumulation value of various repeated signals and produces a rescaled 3-bit valu.tart after striking space key 2 times.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.36-43
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• 2024

Fishing net waste (FNW) constitutes over half of all marine plastic waste and is a major contributor to the degradation of marine ecosystems. While current treatment options for FNW include incineration, landfilling, and mechanical recycling, these methods often result in low-value products and pollutant emissions. Importantly, FNWs, comprised of plastic polymers, can be converted into valuable resources like syngas and pyrolysis oil through pyrolysis. Thus, this study presents a process for generating high-purity hydrogen (H₂) by catalytically pyrolyzing FNW in a CO₂ environment. The proposed process comprises of three stages: First, the pretreated FNW undergoes Ni/SiO₂ catalytic pyrolysis under CO₂ conditions to produce syngas and pyrolysis oil. Second, the produced pyrolysis oil is incinerated and repurposed as an energy source for the pyrolysis reaction. Lastly, the syngas is transformed into high-purity H₂ via the Water-Gas-Shift (WGS) reaction and Pressure Swing Adsorption (PSA). This study compares the results of the proposed process with those of traditional pyrolysis conducted under N₂ conditions. Simulation results show that pyrolyzing 500 kg/h of FNW produced 2.933 kmol/h of high-purity H₂ under N₂ conditions and 3.605 kmol/h of high-purity H₂ under CO₂ conditions. Furthermore, pyrolysis under CO₂ conditions improved CO production, increasing H₂ output. Additionally, the CO₂ emissions were reduced by 89.8% compared to N₂ conditions due to the capture and utilization of CO₂ released during the process. Therefore, the proposed process under CO₂ conditions can efficiently recycle FNW and generate eco-friendly hydrogen product.

• Geophysics and Geophysical Exploration
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• v.12 no.1
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• pp.33-40
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• 2009

In field surveys using the dipole-dipole electrical resistivity method, we often encounter negative apparent resistivity. The term 'negative apparent resistivity' refers to apparent resistivity values with the opposite sign to surrounding data in a pseudosection. Because these negative apparent resistivity values have been regarded as measurement errors, we have discarded the negative apparent resistivity data. Some people have even used negative apparent resistivity data in an inversion process, by taking absolute values of the data. Our field experiments lead us to believe that the main cause for negative apparent resistivity is neither measurement errors nor the influence of self potentials. Furthermore, we also believe that it is not caused by the effects of induced polarization. One possible cause for negative apparent resistivity is the subsurface geological structure. In this study, we provide some numerical examples showing that negative apparent resistivity can arise from geological structures. In numerical examples, we simulate field data using a 3D numerical modelling algorithm, and then extract 2D sections. Our numerical experiments demonstrate that the negative apparent resistivity can be caused by geological structures modelled by U-shaped and crescent-shaped conductive models. Negative apparent resistivity usually occurs when potentials increase with distance from the current electrodes. By plotting the voltage-electrode position curves, we could confirm that when the voltage curves intersect each other, negative apparent resistivity appears. These numerical examples suggest that when we observe negative apparent resistivity in field surveys, we should consider the possibility that the negative apparent resistivity has been caused by geological structure.

• Spatial Information Research
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• v.9 no.2
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• pp.325-340
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• 2001

This research is to construct more useful Geo-spatial data by building spatial data to three dimensional and utilize the database effectively for development of application, maintenance and management program, and application technology, which is on going based on “Haeundae three dimensional database construction project”. Furthermore, the acquisition of geographic information data and the technological improvement of effective construction would be the important factors to judge the qualitative reputation of GIS. Above all, studies to create accurate data and overcome the error limitation are much more important than any other thing. Final form of Spatial Data to materialize efficient GIS(Geographic Information System) must be three dimensional spatial data which has attribute data, actual concept and numerical value of real world. In connection to that, development is on the move to improve building technique of useful spatial data and digitalize the entire country in cryberspace. $\ulcorner the cyber country lrcorner$is designed to mange the entire country systematically. This simulation would be able to cover administration of government institution, public service, corporate business and even the public life in the cyeberspace though the computer. Materialization of efficient GIS and establishment of condition as technically strong nation through the early realization of $\ulcorner the cyber country lrcorner$will provide a great opportunity to open up the global market with exportation of advanced technology.

• Korean Journal of Construction Engineering and Management
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• v.20 no.2
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• pp.28-36
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• 2019

The APR1400 (Advanced Power Reactor 1400MW) nuclear power plant is a large-scale national infrastructure facility with a total project cost of 8.6 trillion won and a project period of 10 years or more. The total project area is about 2.17 million square meters and consists of more than 20 buildings and structures. And the total number of drawings required for construction is about 65,000. In order to design such a large facility, it is important to establish a design standard that reflects the design intent and can increase conformity between documents (drawings). To this end, a design bases document (DBD) reflecting the design bases that extracted in regulatory requirements (e.g. 10CFR50, Korean Law, etc.) is created. However, although the design bases are important concepts that are a big framework for the whole design of the nuclear power plant, they are managed in 2-dimensional by the experts in each field fragmentarily. Therefore, in order to improve the usability of building information, we developed BIM(Building Information Model) based 3-dimensional design bases management system. For this purpose, the concept of design bases information layer (DBIL) was introduced. Through the simulation of developed system, design bases attribute and element data extraction for each DBIL was confirmed, and walls, floors, doors, and penetrations with DBIL were successfully extracted.