• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.6
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• pp.850-858
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• 2002

The present study investigates in detail the combined effects of the Coriolis force and centrifugal force on the development of turbulent flows in a square-sectioned U-bend rotating about an axis parallel to the center of bend curvature. When a viscous fluid flows through a curved region of U-bend, two types of secondary flow occur. One is caused by the Coriolis force due to the rotation of U-bend and the other by the centrifugal force due to the curvature of U-bend. For positive rotation, where the rotation is in the same direction as that of the main flow, both the Coriolis force and the centrifugal force act radially outwards. Therefore, the flow structure is qualitatively similar to that observed in a stationary curved duct. On the other hand, under negative rotation, where these two forces act in opposite direction, more complex flow fields can be observed depending on the relative magnitudes of the forces. Under the condition that the value of Rossby number and curvature ratio is large, the flow field in a rotating U-bend can be represented by two dimensionless parameters : $K_{TC}$ =Re $\sfrac{1}{4}$√λand a body force ratio F=λ/Ro. Here, $K_{TC}$ has the same dynamical meaning as $K_{TC}$ =Re√λ for laminar flow.

• Archives of design research
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• v.16 no.4
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• pp.129-140
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• 2003

As the importance of Culture Technology (music, publication, mobile, film, video, cartoon, animation, character, game, broadcasting etc) is increased, the field of character industry recently has been recognized as an independent brand value beyond the existing view point of simple designing; it also has been given much attention as a main axis leading the cultural industry of the 21 st century. The character of a local government plays roles such as a symbolic part of a region, parts of tourism and public relations, and a profit-making function, which results into generation of regional image and activation of regional economy. However, the present application strategy of the character is only limited to an early stage of regional advertisements. In this context, this study is aimed to investigate and analyze the character development of local governments, especially 31 cities and goons of Gyeonggi Province, comparing with those of local governments of Japan. In the long run, this will provide some suggestions for strategy of character applications. Then, this research is expected to be used as basic reference materials for character development of other local governments and government agencies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.4
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• pp.423-430
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• 2011

The most satisfactory split-beam transducer for fish sizing maintains a wide bearing angle region for correct fish tracking without interference from side lobes and lower sensitivity to fish echoes outside of the main lobe region to correctly measure the angular location of free-swimming fishes in the sound beam. To evaluate the performance of an experimentally developed 50 kHz split-beam transducer, the angular location of a target was derived from the electrical phase difference between the resultant signals for the pair of transducer quadrants in the horizontal and vertical planes consisting of 32 transducer elements. The electrical phase difference was calculated by cross-spectral density analysis for the signals from the pair of receiving transducer quadrants, and the directivity correction factor for a developed split-beam transducer was estimated as the fourth-order polynomial of the off-axis beam angle for the angular location of the target. The experimental results demonstrate that the distance between the acoustic centers for the pair of receiving transducer quadrants can be controlled to less than one wavelength by optimization with amplitude-weighting transformers, and a smaller center spacing provides a range of greater angular location for tracking of a fish target. In particular, a side lobe level of -25.2 dB and an intercenter spacing of $0.96\lambda$($\lambda$= wavelength) obtained in this study suggest that the angular location of fish targets distributing within a range of approximately ${\pm}28^{\circ}$ without interference from side lobes can be measured.

• Journal of Korean Neurosurgical Society
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• v.44 no.4
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• pp.185-189
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• 2008

Objective : The authors present their experiences with stereotactic multiplanar reformatted (MPR) computed tomography (CT)-guided catheter placement for thrombolysis of spontaneous intracerebral hematoma (sICH) and their clinical results. Methods : In 23 patients with sICH, MPR CT-guided catheter placement was used to select the trajectory and target point of hematoma drainage. This group was comprised of 11 men and 12 women, and the mean age was 57.5 years (range, 31-79 years). The patients' initial Glasgow Coma Scale scores ranged from 7 to 15 with a median of 11. The volume of the hematoma ranged from 24 mL to 86 mL (mean 44.5 mL). A trajectory along the main axis of the hematoma was considered to be optimal for thrombolytic therapy. The trajectory was calculated from the point of entry through the target point of the hematoma using reformatted images. Results : The hematoma catheter was left in place for a median duration of 48.9 hours (range 34 to 62 hours). In an average of two days, the average residual hematoma volume was 6.2 mL (range 1.4 mL to 10.2 mL) and was reduced by an average of 84.7% (range 71.6% to 96.3%). The residual hematoma at postoperative seven days was less than 5 mL in all patients. There was no treatment-related death during hospitalization. Conclusion : The present study indicates that stereotactic MPR CT-guided catheter placement for thrombolysis is an accurate and safe procedure. We suggest that this procedure for stereotactic removal of sICH should be considered for the optimization of the trajectory selection in the future.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.7
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• pp.1529-1536
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• 2010

In this paper, we propose a Axially displaced ellipse gregorian antenna with conical feed horn operating in Ku-band. For fast searching satellite position, it is designed the sub-reflector rotates about $1.5^{\circ}$ tilted by the central axis. the curvature and feed center of the main-reflector and sub-reflector are optimized to achieve maximum antenna efficiency. The designed reflector antenna shows the gain of 33dB and the cross polarization level of less than -21dB and the side-lobe level of less than －14 dB at 12.2 GHz. and C/N ratio of 19dB is proved by reception experiment of Koreasat with fabricated antenna.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.141-149
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• 2018

This paper presents a neural network controller design for complex damage to a blended wing Unmanned Aerial Vehicle(UAV): partial loss of main wing and vertical tail. Longitudinal/lateral axis instability and the change of flight dynamics is investigated via numerical simulation. Based on this, neural network based adaptive controller combined with two types of feedback linearization are designed in order to compensate for the complex damage. Performance of two kinds of dynamic inversion controllers is analyzed against complex damage. According to the structure of the dynamic inversion controller, the performance difference is confirmed in normal situation and under damaged situation. Numerical simulation verifies that the instability from the complex damage of the UAV can be stabilized via the proposed adaptive controller.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.10
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• pp.845-855
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• 2018

Cross section design of a prop-blade is carried out for VTOL(Vertical Takeoff and Landing) Quad Tilt Prop-rotor UAV with a maximum takeoff weight of 55 kg and a maximum cruising speed of 180 km/h. Design procedure for cross section design is established and design requirements for prop-blade are identified. Through the procedure, cross section design is carried out to meet the identified requirements. Main design factors including stiffness, weight per unit length, and elastic axis are obtained by using a finite element section analysis program, and the design weight of the prop-blade is predicted. The obtained design factors are used along with the rotor system analysis program CAMRAD II to evaluate the dynamic stability of prop-blade in operating environment. In addition, the prop-blade load is obtained by CAMRAD II software, and it is used to verify the safety of the prop-blade structure. If the design results are not satisfactory, design changes are made in an iterative manner until the results satisfy the design requirements.

• Journal of Korea Water Resources Association
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• v.38 no.7 s.156
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• pp.575-584
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• 2005

The judgement model to warn of possible pollution accident is constructed by multi-perceptron, multi layer neural network, neuro-fuzzy and it is trained stability, notice, and warming situation due to developed standard axis. The water quality forecasting model is linked to the runoff forecasting model, and joined with the judgement model to warn of possible pollution accident, which completes the artificial intelligence warning system. And GUI (Graphic User Interface) has been designed for that system. GUI screens, in order of process, are main page, data edit, discharge forecasting, water quality forecasting, warming system. The application capability of the system was estimated by the pollution accident scenario. Estimation results verify that the artificial intelligence warning system can be a reasonable judgement of the noized water pollution data.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.2
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• pp.79-87
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• 2002

This landscape design proposal was presented to a design competition for the KangWon Province Police Agency(KPA). The site, about 27,711 $m^2$, is located at 293-4 Udu-dong, Chunchun, KangWon-Do. Design objectives of the KPA were to build a symbolic place which fall community members with pride, to elevate an identity and status of the KPA by creating a landscape correspondent to the concept of the building design, to provide community residents with a space to enjoy cultural and social activities, and to make environment friendly space. The main concept was developed by one of characteristics of the traditional spatial structure of Korea known as an, 'Open and Closed spatial structure.'By re-interpreting the traditional spatial structure and applying it to the site, the design met the various desires of the KPA. The site is primarily segmented into 6 sub spaces; entrance space Podori plaza, symbolic court, police billeting area, sports area, and rear rest area. The entrance space, Podori plaza, and symbolic court on the south-west part of the site represent the publicity of the site as the concept of ″open space.″ On the contrary, considering the specialty of police affairs, the north-east part of the site, which contains the police billeting area and rest area, were designed to maintain security by using the concept of ″closed space.″ To express an identity of the KPA, 'Podori', a police mascot, the plaza was designed and is suppose to function as the hub of the community. In the front section of the plaza, a symmetrical planting pattern, centering the strong axis, was introduced to strengthen its symbolic meaning. Traditional window frames such as the pattern of 'Pisal-jige'and 'Umulsal-jige' were used for the paving system which is applied as the environment friendly design. Site facilities and furnitrue were placed at every important spot in order to connect various spaces organically. As these well-tied spaces properly shared their function, spatial sequence and management would be promoted. The entire space was designed to allow free access of handicapped people. This proposal is meant to create a new image of KangWon province and to enhance the way of inhabitants' think about their community.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3C
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• pp.256-268
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• 2007

In this paper, we present a watermarking method for 3-D mesh sequences. The main idea is to transform vertex norm with the identical connectivity index along temporal axis using wavelet transform and modify the distribution of wavelet coefficients in temporally high (or middle) frequency frames according to watermark bit to be embedded. All vertices are divided into groups, namely bin, using the distribution of coefficients in low frequency frames. As the vertices with the identical connectivity index over whole frames belong to one bin, their wavelet coefficients are also assigned into the same bin. Then, the watermark is embedded into the wavelet coefficients of vertex norm. Due to the use of the distribution, our method can retrieve the hidden watermark without any information about original mesh sequences in the process of watermark detection. Through simulations, we show that the proposed is flirty robust against various attacks that are probably concerned in copyright protection of 3-D mesh sequences.