• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.210-213
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• 1999

수동소나체계에서 음원의 위치와 관련된 매개변수를 산출하기 위해 정합장처리(Matched Field Processing)가 이용된다 본 연구에서는 수직선배열센서를 이용한 정합장처리에서 음원 위치추정에 영향을 미치는 다양한 요인 중, 수직음속분포 오정합(mismatch)에 의한 영향을 MV 프로세서 (Minimum Variance Processor)를 이용하여 모의실험함으로써 그 결과를 분석하였다. 천해 모의환경에서 동일한 기울기로 증감하는 수직음속분포 오정합은 음원 위치추정에서 거리성분의 오차를 가지며, 상이한 기울기를 갖는 수직음속분포 오정합은 거리와 수심 성분의 오차가 유발됨을 확인할 수 있었다. 심해 모의 환경에서 수직음속분포 오정합은 거리와 수심 성분의 오차가 유발되고, 거리추정의 전반적인 경향은 천해의 동일한 기울기를 가지는 경우와 유사함을 확인할 수 있었다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.309_310
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• 2009

본 연구에서는 가공배전선로의 상하단 단락고장을 예방하기 위하여 현행 관련 기준의 적정성 여부를 검토하고자 한다. 이를 위하여 기준이도, 완철의 최소 이격거리, 미국 NESC(National Electric Safety Code)의 수직선간이격거리에 대하여 문헌적 고찰을 한 후, 이를 토대로 국내에 적용할 수직선간이격거리 및 지상고 검토 조건을 도출하였고, 기준이도 적용 시 가공배전선 종류별 75^{\circ}C$이도를 계산하여 그 결과들을 비교 검토하였다. 그 결과 상하단 선간단락 고장을 예방하기 위하여 나전선의 기준이도를 특고압전선과 동일하게 적용하여야 하며, 특고압 완철 간의 최소이격거리는 경간 100m 이상에서 수직이격거리가 부족하므로 0.1m 정도 증가 시키는 것이 바람직하다는 것을 발견하였다.

• Journal of Aerospace System Engineering
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• v.9 no.3
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• pp.12-16
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• 2015

인간동력 항공기 TORUK MAKTO I에 대하여 양력선이론 및 XFOIL을 사용하여 도출한 공력계수 및 미계수 값과 CATIA를 사용한 관성모멘트 추정 값을 사용하여 지면효과 및 주익과 무게중심 사이의 수직거리 변화가 인간동력 항공기의 세로 정안정성에 미치는 영향과 수평미익(스테빌레이터) 변위각제어에 따른 세로 동안정성 해석 연구를 수행하였다. 연구결과 지면효과가 정적여유에 미치는 영향은 미미했다. 공력중심과 무게중심 사이의 수직거리가 세로 정안정성에 미치는 영향은 매우 컸으며, 수직거리 증가는 세로 정안정성을 증가시켰다. 수평미익 변위각 제어에 따른 세로 동안정성 해석 결과 장주기 진동특성과 감쇄특성이 매우 나쁜 것으로 나타났다. 향후 항공기의 동특성을 고려한 세로 동안정성 해석 및 측풍에 의한 가로 및 방향 안정성 해석연구를 수행할 예정이다.

• The Journal of the Korean dental association
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• v.24 no.12 s.211
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• pp.1061-1068
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• 1986

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.1
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• pp.1-5
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• 2011

Purpose: Measurement of the horizontal and vertical prism diopter was investigated which was occurred due to distance differences between the optical inter-centeral distance (OC) and the interpupillary distance (PD) of the prescribed glasses. Methods: We surveyed 96 subjects (192 eyes) at the average age of 21.56 years old. The PD was measured by using the PD measurement system (DONGYANG PD-85, Korea), and the OC of the glasses was measured by using the projective peak refractive power measurement system (TOPCON CL-200, Japan). The OH value was measured by using Penlight and the PD ruler. Results: The PD which had been measured by the PD system and the OC of the glasses revealed 78.1% of differences. 62.5% of the objects were base-in value prescribed glasses; 58.3% were out of permissible error. Only 8 subject showed concurrence between the prescribed glasses and the OH value, and 82.3% of the objects were induced vertical prism of over 1 (prism diopter). Conclusions: In order to improve the vision function of people who wear glasses, it is necessary to advance the accuracy of PD, OH measurement and making glasses as well.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.6
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• pp.53-60
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• 2002

Based on the analyses of the single transverse injection in supersonic flow fields, the mixing characteristics of dual transverse injection of hydrogen in supersonic air flow are studied with computational methods. Three-dimensional Navier -Stokes and the k-$\omega$ SST turbulence model were used. A parametric study is conducted with the variation of the distance between two injectors. The flow patterns and the mixing characteristics of two injection flows are very different from each other, and the flow patterns and the mixing characteristics of the rear injection flow are strongly influenced by those of the first injection flow. The increase of the distance between two injectors up to a specific distance results in the increase of mixing rate and penetration of fuel. However, the increase of the distance over the specific distance results in the decrease of mixing rate and penetration of fuel. From the results it can be stated that there exists a distance between two injectors for optimum mixing characteristics.

• Asian Journal of Turfgrass Science
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• v.20 no.2
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• pp.203-211
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• 2006

This study was initiated to investigate the difference of playing ability among soccer fields established with natural turfgrass, artificial turf and bare ground. The soccer fields with natural turfgrasses were established with cool-season grass(Kentucky bluegrass 80%+Perennial ryegrass 20%) and zoysiagrass. The artificial turf field was constructed with Konigreen $DV5000^{TM}$. Bare ground was sandy soil. Data such as ball rolling distance and vertical ball rebound were collected at the Sports Science Town of Konkuk University from 2005 to 2006. A ball in the study was Hummel Air Vision #1, certified by KFA(Korea Football Association) in ball pressure of 1.01b. Ball rolling distance was the longest on bare ground(13.6m), followed by artificial grass(11.4m), cool-season grass(7.8m) and zoysiagrass(4.7m). It decreased with lower frequency in use, stronger rigidity and higher density of turfgrass. Vertical ball rebound was the highest on bare ground(1.0m), followed by artificial grass(0.9m), cool-season grass(0.6m) and zoysiagrass(0.4m). It was lower under conditions of low use frequency, strong rigidity, and high density. Both ball rolling distance and vertical ball rebound were not greatly affected by cool-season grass maintained with high intensity of culture by years after establishment. However, zoysiagrass field under low intensity of culture showed longer in ball rolling distance and higher in vertical ball rebound with time after establishment.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.303-308
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• 2013

A remote controlled sprayer has designed, manufactured and experimented to spray well on pear trees with pesticides. This study was executed to automate pest management of pear trees. Types of spray nozzle, which was used on the system, were analyzed experimentally to find an optimal spray equipment configuration with several nozzles. Attributions of ultrasonic sensors were analyzed to adjust spraying distance of an unmanned sprayer system. This paper investigated shapes of pear trees and cultivating environment of pear orchard. In order to select optimal spray environment, liquid distribution was measured while angle of nozzle was changed. Additionally, liquid distribution by distance and sprayed liquid capacity by side distance were measured. According to information of shapes of pear trees and cultivating environment of pear orchard, sprayer frames of an unmanned sprayer system were manufactured and sprayer frames were suitable for interval of pear trees. The sprayer system could adjust width of sprayer frames to 2.5 m and height of sprayer frames to 1.7 m. Optimal angle of nozzle, and optimal distance between objects and nozzle were $15^{\circ}$ and 0.8 m. When side distance was placed from 1.2 m to 1.8 m, sprayed capacity reached to the highest amount.

• Economic and Environmental Geology
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• v.50 no.3
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• pp.225-238
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• 2017

In this study, two viable measures of mean length and cumulative thickness of sand layers as important spatial statistics responsible for optimal SAGD (Steam Assisted Gravity Drainage) location for oil sand development were compared. For the comparisons, various deposits composed of sand and clay media were realized using a geostatistical simulator and the extent of steam chamber is simulated using multiphysics numerical simulator (dualphase flow and heat transfer). Based on the spatial statistics of each realization and the corresponding size of simulated steam chamber, the representativeness of two candidate measures (cumulative thickness and mean length of permeable media) were compared. The results of the geostatistical and SAGD simulations suggest that the mean length of permeable media is better correlated to the size of steam chamber than the cumulative thickness. Given those two-dimensional results, it is concluded that the cumulative thickness of the permeable media alone may not be a sufficient criterion for determining an optimal SAGD location and the mean length needs to be complementarily considered for the sound selections.

• Aerospace Industry
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• s.108
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• pp.66-67
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• 2010

수직이착륙, 영어로는 VTOL(Vertical Take-Off and Landing)이라 불리는 기술은 공기역학을 거부한 첨단 항공우주기술이다. 일반적으로 고정익 항공기는 날개에서 발생하는 양력으로 하늘을 날지만 VTOL 항공기는 순수한 엔진 추력만으로 수직으로 이착륙하거나 단거리에서 이륙할 수 있다. 다만 높은 기술적 완성도를 요구하는 만큼 현재까지 실전 배치된 군용기 중 이 기술이 적용된 군용기는 해리어(Harrier)와 V-22 오스프리(Osprey), Yak-38 정도가 고작이다. 수직이착륙 기술에 대해 소개한다.