• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.1
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• pp.25-32
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• 1983

The corner reflector is used to increase the echoing area of radar targets in the air, and it can also be applied to increase the echoing area of the sonar targets under water. As the basic research for this application, the authors investigated the ultrasonic reflection characteristics under water for the corner reflector which was made of aluminum plate. The experiments were made by pulse measuring method with the magnetostrictive ferrite transducers of 28, 50 and 75KHz in the experimental water tank. The results obtained are as follows; 1. The target strength of corner reflectors were increased in proportion to the diameter and were greater at higher frequency of 75KHz than at lower frequency of 28KHz. 2. In the case of 5 corner reflectors of 150mm in diameter which have corner angles of 15$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$, 60$^{\circ}$ and 90$^{\circ}$the measured values of the maximum target strength at 75KHz were-25.0 dB, -17.2dB, -15.1dB, -13.4dB and 11.0dB, and then the number of main lobes showing the maximum target strength in the backscattering patterns were 24, 12, 8, 6 and 4, respectively. 3. When 7 corner reflector of 80mm in diameter and 90$^{\circ}$ in the corner angle was located on the minor axis of the horizontal section with directional angles of 0$^{\circ}$, 2.5$^{\circ}$, 5.0$^{\circ}$, 7.5$^{\circ}$, 10$^{\circ}$ and 12.5$^{\circ}$ against the sound beam axis, the measured values of the target strength on each position at 75KHz were -21.2dB, -21.9dB, -26.0dB, -30.5dB and -36.8dB, respectively.

• The Journal of the Korea Contents Association
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• v.11 no.4
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• pp.67-73
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• 2011

The image retrieval generally shows the same or similar images to a query image as a result. In the case of rotated image, however, its performance tends to be debased significantly. We propose a method to ensure a reliable image retrieval of rotated images as follows; First, to obtain feature points of query/DB images by Harris Corner Detector; and then, utilizing the feature points, to find the object's axis and query/DB images into rotation invariant images with Principal Components Analysis algorithm. We have experimented with 6,000 natural images which are 256 pixels in diameter. They are 1,000 Wang's images and their rotated images by $30^{\circ}$, $45^{\circ}$, $90^{\circ}$, $135^{\circ}$ and $180^{\circ}$. The simulation results show that the proposed method retrieves rotated images more effectively than the conventional method.

• Clinics in Shoulder and Elbow
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• v.21 no.3
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• pp.113-119
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• 2018

Background: This study was undertaken to evaluate the positional relationship between planes of the glenoid component (the scapular plane and the perpendicular plane to the glenoid) and its surrounding structures. Methods: Computed tomography (CT) images of both shoulders of 100 patients were evaluated using the 3-dimensional CT reconstruction program ($Aquarius^{(R)}$; TeraRecon). We determined the most lateral scapular bony structure of the scapular plane and measured the shortest distance between the anterolateral corner of the acromion and the scapular plane. The distance between the scapular plane and the midpoint of the line connecting the posterolateral corner of acromion and the anterior tip of the coracoid process (fulcrum axis) was also evaluated. The perpendicular plane was then adjusted to the glenoid and the same values were re-assessed. Results: The acromion was the most lateral scapular structure of scapular plane and perpendicular plane to the glenoid. The average distance from the anterolateral corner of the acromion to the scapular plane was $10.44{\pm}5.11mm$, and to the plane perpendicular to the glenoid was $9.55{\pm}5.13mm$. The midpoint of fulcrum axis was positioned towards the acromion and was measured at $3.90{\pm}3.21mm$ from the scapular plane and at $3.84{\pm}3.17mm$ from the perpendicular plane to the glenoid. Conclusions: Our data indicates that the relationship between the perpendicular plane to the glenoid plane and its surrounding structures is reliable and can be used as guidelines during glenoid component insertion (level of evidence: Level IV, case series, treatment study).

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.598-605
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• 1985

Laminar natural convection heat transfer past an outer rectangular corner was experimentally investigated by using Mach-Zehnder interferometer. The present geometry represents the case when the plume from a vertical flat plate and that from a horizontal one merge into a single plume. the temperature distribution and the local heat flux were measured in the range of Grashof number 8 * 10$^{4}$$r_{LH}$ <1.25 * 10$^{6}$ . The effect of the geometric aspect ratio was also considered. Correlation for the average Nusselt number vs. Grashof number was obtained by using a newly determined characteristic length. To determine the interaction of the plumes, the present results were compared with the similarity solutions available from the isolated vertical and isolated horizontal flat plates.

• Journal of the Society of Disaster Information
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• v.15 no.1
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• pp.98-108
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• 2019

Purpose: The purpose of this study is to test the sprinkler performance to protect the wall and ceiling joints of the sandwich panel warehouse in case of fire. Method: Based on the field surveys, test was setup and combustibles were prepared. The sprinkler discharge tests were performed at the corner of the wall and right under the sprinkler head. Results: It has been found that operation of the K-80 closed sprinkler head prevents the ignition of the sandwich panel and therefore no damage to the joints of sandwich panels. To prevent skipping phenomenon, it is necessary to install the sprinkler head from the corner of the wall and to keep a minimum distance of 2.4m and a maximum distance of 3m. Conclution: A Standard Operation Procedure should be prepared to suppress and rescue of fire brigade for a sandwich panel warehouse protected by perimeter sprinklers preventing a ignition of core materials and control fire.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.3
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• pp.77-86
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• 1994

A New environment SENSATION for circuit optimization and statistical analysis has been developed. It provides real time simulation and includes automatic algorithms to assist for reaching optimal solution. Furthermore, statistical analysis environment is presented which aids in Monte Carlo analysis. worst case corner analysis, and sensitivity analysis. These capabilities faciliate the characterization of the effects of several operating conditions and manufacture process paramenters on the design performances. We verify that the proposed methods can obtain the optimal solution of the objective function through several experimental results.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.67-74
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• 1999

When high speed train meets sidewind, folwfields around the train is very complex. In this case, the force by sidewind has a bad effect on stability of train. We can observe that the flow separates, reattaches, and forms all unsteady vortex in the wake region behind tile structure. Such folwfield can be analyzed by $\kappa$-$\omega$ SST model, and we investigate the effect for various section shape of high speed train. So we acquire the result that as tile corner of train section is rounder, stability of train is better.

• Wind and Structures
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• v.28 no.3
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• pp.191-201
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• 2019

In this paper, the aerodynamic analysis of a vertical axis wind turbine was carried out by CFD approach to optimize the turbine performance. To perform numerical simulation, SST-Transition turbulence model was used, which demonstrated more precise results compared to non-transition models. A parametric study was conducted to optimize the VAWT performance based on the selected model. The investigation of pitch angle changes showed that the highest power produced by the turbine occurs at $2^{\circ}$ angle. Considering the effect of the rotor's arm junction to the airfoil showed that by increasing the distance of the junction from the edge of the airfoil from 25 cm to 40 cm, the power of the turbine increases by 60%. However, further increase in this distance results in power decrease. Based on the proposed numerical model, a case study was conducted to consider the installation of four VAWTs in the southwest corner of the medical science building at TMU campus with a height of 42m. The results of the simulation showed that 8.27 MWh energy is obtainable annually.

• The KSFM Journal of Fluid Machinery
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• v.17 no.5
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• pp.27-36
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• 2014

This paper presents a numerical investigation of the effect of the rotation speed on the performance in a transonic axial compressor with the dihedral stator. Four stator geometries with different stacking line variables were tested in the flow simulations over the whole operating range. It was found that a large shroud loss at the rotor outlet and the subsequent shroud corner separation in the stator passage occurred at low mass flow rate with the 100 % design speed. The hub dihedral stator could suppress the shroud loss region and consequently improve the stall margin. In case of the 70 % design speed condition as the mass flow rate decreased, it was seen that the high loss region was placed at the midspan of the rotor passage. The dihedral stator slightly affected the local diffusion factor, but the performance of the compressor was not changed.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2011.04a
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• pp.147-152
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• 2011

The purpose of this study is to find out the commercialization cause of 2nd class residential area in urban center as basic research to protect urban residential area against the pressure of commercialization. Through the research that are based on literature, field survey and urban planning map, it analysed the commercialization cause of selected two sites under similar urban condition ; to be a nearby subway station and to be a famous commercial street in site, etc. The consequences of this study are summarized as follows ; First the distance between subway station and residential block and residential commercialization are in inverse proportion each other. Second, the corner lot of a block and the access street directly connected collector street are very important factors to spread commercialization to residential area. Finally, nevertheless first and second results, there is square zone which is very high rate of commercialization within one regardless the distance between subway and residential block. the maximum range of square zone is assumed about 250 meter based on case study.