• Wind and Structures
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• v.4 no.1
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• pp.63-72
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• 2001

This paper presents results of a study on wind loads and wind induced dynamic response of bridge jointed twin-towered buildings. Utilizing the high-frequency force balance technique, the drag and moment coefficients measured in wind tunnel tests, and the maximum acceleration rms values on the top floor of towers, are analyzed to examine the influence of building's plan shapes and of intervals between towers. The alongwind, acrosswind and torsional modal force spectra are investigated for generic bridge jointed twin-towered building models which cover twin squares, twin rhombuses, twin triangles, twin triangles with sharp corners cut off, twin rectangles and individual rectangle with the same outline aspect ratio as the twin rectangles. The analysis of the statistical correlation among three components of the aerodynamic force corroborated that the correlation between acrosswind and torsional forces is significant for bridge jointed twin-towered buildings.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.49-56
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• 2004

A two-dimensional twin-jet counterflow system has been designed, in which two streams from two double-slit nozzles form a counterflow. This flow system enables one to systematically investigate various effects on non-premixed flames, including the non-premixed flame interaction, the edge flame behavior and the effect of curvature. Non-premixed flame interaction in the twin-jet counterflow system has been investigated numerically for methane fuel diluted with nitrogen. Three types of non-premixed flame(conventional counterflow flame, crossed twin-jet flame and petal shaped flame) were simulated depending on the combination of fuel/oxidizer supply to each nozzle. The extinction characteristics of non premixed methane flame in the twin-jet counterflow have been investigated numerically. The boundary of the existence of petal-shaped flames was identified for the twin-jet counterflow flames. Due to the existence of the unique petal-shaped flames, the extinction boundary for the twin-jet counterflow can be extended significantly compared to that for the conventional counterflow non-premixed flames, through the interaction of two flames. Through the comparison of the crossed twin-jet flame and the conventional counterflow flame, structure of the crossed twin-jet counterflow flame is analysed. Through the comparison of the petal shaped flame and the conventional counterflow flame, the extension of the extinction boundary for the twin-jet counterflow is investigated.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.17-19
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• 2002

Melt textured YBCO superconductors were fabricated by the top seeding method using Sml.8($Sm_{1.8}$ $Ba_{2.4}$ $Cu_{3.4}$$O_{7-Y}$) seed. We investigated the twin structures using the optical microscope, SEM and TEM. The twin structures formed during the tetragonal to orthorhombic transition which occurred at $450^{\circ}C$ in sample oxygen annealing. The twin structures were clearly observed by SEM due to the chemical etching effects. The lengths of twin structures were increased as the oxygenation heat treatment time increased from 1hr to 10hr. We investigated twin structure by TEM. The twin spaces were considered to be related to the oxygen contents. The results suggested an oxygen diffusion model for the formation of the twin lengths.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.1
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• pp.15-22
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• 2004

Twin-skeg type stern shapes are recently adopted for very large commercial ships. However it is difficult to apply a CFD system to a hull form having twin-skeg, since grid topology around a twin-skeg type stern is more complicated than that of a conventional single-screw ship, or of an open-shaft type twin-screw ship with center-skeg. In the present study a surface mesh generator and a multi-block field grid generation program have been developed for twin-skeg type stern. Furthermore, multi-block flow solvers are utilized for potential and viscous flow analysis around a twin-skeg type stern The present computational system is applied to a 15,000TEU container ship with twin-skeg to prove the applicability. Wave profiles and wake distribution are calculated using the developed flow analysis tools and the results are compared with towing tank measurements.

• International Journal of Advanced Culture Technology
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• v.10 no.3
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• pp.397-403
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• 2022

The world is paying a lot of attention to digital twins to preoccupy future technological competitiveness. Digital twins can be used in various fields such as manufacturing, medical care, and cities. Various market research institutes predict that the market size of digital twins will gradually expand. Korea has also selected digital twin as one of the representative tasks of the Korean version of the New Deal and is promoting related policies. However, a common platform or standard for building digital twins is not enough. Interoperability is a very important characteristic for the purpose of creating new value through interconnection between digital twins rather than independently developing and utilizing digital twins. The Digital Twin Consortium is an international council for the effective development and utilization of digital twins, and is working to solve the problem of digital twin interoperability. The Digital Twin Consortium recently published the 'Digital Twin System Interoperability Framework', and this paper analyzes the digital twin interoperability based on it.

• Journal of Embryo Transfer
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• v.11 no.3
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• pp.301-307
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• 1996

This study was carried out to produce twin calves by embryo transfer in Hanwoo and investigate the pregnancy and twin rate by recipient's conditions. All recipients were bred at estrus by artificial insemination with Hanwoo semen and then transfered an additional embryo produced in vivo or in vitro to tbe uterine horn contralateral to the corpus luteum on Day 7. The results obtained were as follows ; 1. The pregnancy rate was higher in young recipients of 3 years (68.8%) than in old ones of 10 years and greater(36.4%). And for CL size pregnancy rate was 57.9, 45.4 and 60.1% in large, medium and small size of CL of recipients, respectively. 2. 447recipients were transferred an additional embryos at 7th day after Al and average pregnancy rate was 57.5% and twin production rate was 22.2%. 3. Average pregnancy and twin production rate by direct transfer methods of frozenthawed IVF embryos was 56.0 and 16.7%. 4. The ratio of male to female twin in a total of 55 twin pairs was 54.6%, and average gestation lengths of male to female and female to female twin were 280.6$\pm$5.4 and 279.715.4 days, respectively. Average birth weight of twins was beavior in male and male twin(23.2i5.8kg) than in male and female twin(20.5$\pm$2.6kg).

• Korean Journal of Veterinary Research
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• v.52 no.2
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• pp.141-146
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• 2012

Calving records of Holstein dairy cows from 2005 to 2010 comprising Goyang and Paju cities herd with 2,362 calving events representing 240 twin births were used to evaluate the effect of abomasal displacement and retained placenta after single or twin births on fertility. In retained placenta cows, the period of twin pregnancy (mean 270.5 days) was shorter than that of single pregnancy (mean 274.8 days), however first artificial insemination period (twin: mean 107.4 days, single: mean 92.0 days), non-pregnant period (twin: 154.8 days, single: 132.2 days), and number of insemination (twin: mean 2.00 times, single: mean 1.87 times) of twin pregnancy were increased as compared with single pregnancy. In abomasal displacement cows, first artificial insemination period (twin: mean 122.9 days, single: mean 106.0 days), non-pregnant period (twin: 172.4 days, single: 152.0 days), and number of insemination (twin: mean 2.16 times, single: mean 1.89 times) of twin pregnancy were increased as compared with single pregnancy. The prevalence of complication such as retained placenta, abomasal displacement with single or twin births increased first artificial insemination period, non-pregnant period, and number of insemination period.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.1
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• pp.134-143
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• 1998

Twin Blocks are simple bite-blocks that effectively modify the occlusal inclined plane to induce favorably directed occlusal forces by causing a functional mandibular displacement. These devices use upper and lower bite-blocks that engage on occlusal inclined planes. Twin Blocks use the forces of occlusion as the functional mechanism to correct the malocclusion. To get an excellent result in the treatment by using the Twin Block appliances, proper case selection must be needed. Twin Block treatment is performed in two stages. Twin Blocks are used in the active phase to correct the anteroposterior relationship and establish the correct vertical dimension. Once this phase is accomplished, the Twin Blocks are replaced with an upper Hawley type of appliance with an anterior inclined plane, which is then used to support the corrected position as the posterior teeth settle fully into occlusion. The Twin Block is the most comfortable, the most esthetic ane the most efficient of all the functional appliances. Twin Blocks have many advantages compared to other functional appliances. Patients can wear Twin Blocks 24 hours per day and can eat comfortably with the appliances in place. From the moment Twin Blocks are fitted, the appearance is noticeably improved. There is less interference with normal function. Integration with conventional fixed appliances is simpler than with any other functional appliance. Twin Blocks allow independent control of upper and lower arch width. Appliance design is easily modified for transverse and sigittal arch development. The authors treated Class II malocclusion with Twin Blocks. and the results as follows; 1. Rapid profile improvement was achieved in 2-3 months. 2. There was excellent patient cooperation. 3. Severe overjet and overbite were reduced. 4. Class II molar relationship was changed to Class I.

• Journal of the Korea Society for Simulation
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• v.29 no.2
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• pp.11-20
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• 2020

As the manufacturing environment becomes more complex, traditional simulation models alone are having a lot of difficulties in reflecting real-time manufacturing situations. Although the Digital Twin concept is actively discussed as an alternative to overcome theses issues, many studies are being carried out only in the product design phase. This research presents a Digital Twin-based manufacturing environment framework for applying the Digital Twin concept to the manufacturing process. Twin model that is operated in virtual space, physical system and databases describing the actual manufacturing environment, are proposed as detailed components that make up the framework. To check the applicability of proposed framework, a simple Digital Twin-based manufacturing system was simulated in a conveyor system using Arena software and Excel VBA. Experiment results have shown that the twin model is transmitted real time data from the physical system via DB and were operating in the same time unit. The Excel VBA fitted parameters defined by cycle time based on historical data that real-time and training data are being accumulated together. This study proposes operating method of digital twin model through the simple experiment examples. The results lead to the applicability of Digital twin model.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.392-405
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• 2014

SSPA experiences a growing interest in twin skeg ships as one attractive green ship solution. The twin skeg concept is well proven with obvious advantages for the design of ships with full hull forms, restricted draft or highly loaded propellers. SSPA has conducted extensive hull optimizations studies of LNG ships of different size based on an extensive hull data base with over 7,000 models tested, including over 400 twin skeg hull forms. Main hull dimensions and different hull concepts such as twin skeg and single screw were of main interest in the studies. In the present paper, one twin skeg and one single screw 170 K LNG ship were designed for optimally selected main dimension parameters. The twin skeg hull was further optimized and evaluated using SHIPFLOW FRIENDSHIP design package by performing parameter variation in order to modify the shape and positions of the skegs. The finally optimized models were then built and tested in order to confirm the lower power demand of twin skeg designed compaed with the signle screw design. This paper is a full description of one of the design developments of a LNG twin skeg hull, from early dimensional parameter study, through design optimization phase towards the confirmation by model tests.