• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.3 s.309
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• pp.41-50
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• 2006

This paper presents a novel ultrasonic sensor system to overcome limited distance detection range that can be measured only more than 30cm by single ultrasonic transducer. This is accomplished by separation of receiving capacitive ultrasonic transducer from transmitting capacitive ultrasonic transducer. And hardwares and software of the system are described in detail. The system makes very close range as well as long range detect by wireless precisely. Frequency of trigger pulse is 10Hz, but it is very low frequency for transmitting data in wireless module. Therefore, for triggering between receiver and transmitter, an algorithm for mixing and distinguishing trigger pulse from carrier pulse by software is proposed. The system is designed by common microprocessor 8051. The performance of the proposed method has been assessed through two types. The first, transmitting and receiving transducer are put on both sides. And then, distance of two point is measured as far as 0mm. Secondly, transmitting transducer send out ultrasonic pulse and measure the time of flight(TOF) until a first echo from an object detected by the detached receiving transducer. The distance between the detached transducers and a reflecting object is measured as far as 7cm. Images of measured ultrasonic waves and TOF for two methods presented to prove effectiveness of results.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.141.2-141.2
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• 2012

We present photometric solutions of the 26,212 eclipsing binaries discovered in the LMC by Graczyk et al. (2011). They published that 70 percent of a total are detached systems. Another 25 and 5 percent are semi-detached and contact binaries, respectively. We discovered that 21 percent of 26,121 eclipsing binary stars are eccentric orbit systems. The binary star distribution in the LMC is different from those of the Galactic center direction (Bade window). It is very interesting that there are only 5 of 357 (2 percent) stars have eccentric orbit in the Galactic Center (Kang 2011). We selected the light curve of 18,274 detached systems. Then we estimated the fundamental parameters on the basis of their photometric solutions and the semi-major-axis (a) assuming the distance modulus to the LMC~18.50. We compared the estimated fundamental parameters with an empirical mass-luminosity relation and consistency between mass-radius relation base on stellar evolution model in the low metallicity (Z=0.008) by Bertelli et al. (2009). This method allows for independent determine of the fundamental parameters of the eclipsing binaries in the LMC without the radial velocity curves.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.2
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• pp.99-110
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• 2010

The DES analysis of strong compressibility flow, LES mode is intentionally performed in boundary layer with the conventional empirical constant $C_{DES}$ value of 0.65. In this study, an expression is suggested to determine the $C_{DES}$ value dynamically by using a distribution function of the ratio of turbulence length scale and wall distance which is used in S-A DDES model for RANS mode protection. The application of the dynamic $C_{DES}$ presents better prediction than previous results those used constant but different $C_{DES}$ values.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.7
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• pp.8-13
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• 2019

As increasing demand for precise machining in advanced disciplines, especially in semi-conductor, aeronautical and automotive industries, the magnetic abrasive deburring(MAD) which is able to eliminate micro-sized burr on complex surface in less time has drawn the attention in the last decades. However, the performance of MAD is subject to shape and size of a tool. Therefore, this study aim to identify deburring behavior of MAD in U-type flow channel by measuring the length rate of burr removal in radial distance of the cylindrical tool under four process factors. In order to evaluate the deburring effect of MAD on the surface, finishing regions are divided based on center of the circular cutting tool. As a results, it was defined that the amount of burr removal in a downward direction moving toward flow channel from the top surface was higher than upward direction. This is because the magnetic abrasives were detached from magnetic lines of force due to geometrical shape.

• Journal of the Korean housing association
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• v.12 no.4
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• pp.163-171
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• 2001

The purpose of this study was to analyze the view of housing of Korean and Japanese female university students. The view of housing was investigated in four stages-housing consciousness, resident opinion, ideal housing and housing needs-in this study. The data was collected through the self-entry questionnaire designed for this study and the sample of 400 in total, 200 cases form Korea and 200 cases form Japan. The results are as follows : The major findings of the housing consciousness were that Japanese female university students preferred the detached in the future. The resident opinion of Korean and Japanese female university students showed that the group space was more important than the private space. In the ideal image, they wanted psychological and physical comfort from their houses. In the housing needs, Korean have considered the distance of friend and family and been satisfied with interior design, whereas Japanese have considered the expression of social level and been satisfied with outdoor design.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.193-193
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• 2016

In past decades beach erosion has been remarkably severe along coasts of different parts of the world, so that distinct types of coastal protective measures have been implemented; seawalls, wave-dissipating breakwaters, groins, artificial headlands or detached breakwaters have been constructed. In recent years, at Bongpeong beach, South Korea, an artificial headland was constructed to stop the beach erosion. The structure resulted in severe beach erosion of the adjoining places. In order to stop the consequences, another headland was constructed at some distance, but the construction of double headland did not prevent the erosion significantly. This paper focuses on the accurate design of the artificial double headland construction. The study presents the application of equilibrium shoreline empirical formula of parabolic type to estimate the equilibrium stages of the artificial double headland beaches and an analytic solution is presented in the present study. The research has solved the empirical formula of parabolic type to find the optimum result by considering the essential parameters that influence the erosion after the construction of double headland.

• Land and Housing Review
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• v.11 no.3
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• pp.1-9
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• 2020

This study fulfills an empirical analysis how the physical factors affect the formation of housing price with the block unit. Block unit houses are a type of housing that pursues comfort and convenience in that the characteristics of individual houses and apartment houses are mixed. Existing studies have focused only on the physical characteristics of various planning elements such as block-type residential complexes. Nevertheless, it is not known whether the physical characteristics of block-type residential complexes reflect the preferences of actual consumers. In addition, there are no sufficient studies on how to evaluate them from the market side. In this study, block-level detached housing sites the target complexes with 10 or more households built between 2002 and 2019. The target areas for analysis are 163 complexes in Paju, Namyangju, Goyang, Suwon, Yongin, Ansan, Gimpo, Incheon, Seongnam, Hwaseong and Gwangju, Gyeonggi-do. The physical elements that make up the unit housing were classified through factor analysis. Finally, regression analysis was conducted to establish the basis determining the price-forming factors. As a result of the analysis, the factors that influenced the price were the site area and the number of community facilities. The variable with negative influence was the distance from Seoul. Based on the results of this study, it can be said that the influence on price formation in various areas was confirmed by presenting the relationship between the facility composition and price of a detached house.

• KIEAE Journal
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• v.14 no.5
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• pp.89-96
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• 2014

This study provides the basic resource for establishing the environment design policies around elementary school for the students and analyzes the actual pedestrian environment conditions of elementary school in order to improve safety of from crime for them. For this, the field survey are conducted on risk of from crime in 10 sidewalks of 5 elementary schoolin Ilsan new town. The result of this are the followings ;1) There are schools which have difference between the height of road and the height of pedestrian path. 2) There are schools which are insufficient distance for securing front sight because of shape of pedestrian path. 3) In entrance there are facilities interfering with natural surveillance within school boundaries such as stone written school motto, storehouse, wash room, doorpost. 4) In entrance there are schools with no security office, emergency bell and CCTV. 4) The openness in the bottom of fence is lower than that of upper because of shrubs and material of fence. 5) There are concealed places and cars in back gate area interfering with natural surveillance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.768-773
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• 2004

When a gas expands through a convergent nozzle in which the ratio of the ambient to the stagnation pressures is higher than that of the critical one, the issuing jet from the nozzle is underexpanded. If a flat plate is placed normal to the jet at a certain distance from the nozzle, a detached shock wave is formed at a region between the nozzle exit and the plate. In general, supersonic moist air jet technologies with nonequilibrium condensation are very often applied to industrial manufacturing processes. In spite of the importance in major characteristics of the supersonic moist air jets impinging to a solid body, its qualitative characteristics can not even know. In the present study, the effect of the nonequilibrium condensation on the underexpanded moist air jet impinging on a vertical flat plate is investigated experimentally. Flow visualization and impact pressure measurement are performed for various relative humidities and flat plate positions. The obtained results show the plate shock and Mach disk are dependent on the nozzle pressure ratio and the relative humidity, but for a given nozzle pressure ratio, the diameters of the plate shock and Mach disk depend on the stagnation relative humidity. The impact pressure deviation from the flow of without condensation is large, as the relative stagnation humidity increases.

• Journal of the Korean Geosynthetics Society
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• v.1 no.1
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• pp.13-21
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• 2002

Geotextile tubes hydraulically or mechanically filled with dredged materials have been applied in hydraulic and coastal engineering in recent years(detached breakwater, groins and jetty). The geotextile tubes are made of sewn geosynthetics sheets. If the sandy soil is use to fill material, these inlets should be spaced closely to assure uniform filling of the tubes because sandy soil and geosynthetic is very pervious. However, the clayey soil or contaminated slurry is used, the inlets can be located relatively long distance. The fine clayey particles tend to rapidly blind the fabric slowing down water escape through the geotextile. This paper presents a field test result of a geotextile tube in the land reclamation project for the Songdo New City construction site. The dredged silty clay was dredged by the dredging ship and hydraulically pumped into the geotextile tube. The height of geotextile tube was measured at every filling stage and also measured width and diameter of geotextile tube with the elapsed time. Based on the test results, if the clayey filling material is used, the pumping step must be divided 3~4 stages for drainage and sediment. After complete drainage, the height of the geotextile tube reduces by approximately 50%.