• Title/Summary/Keyword: KAU

Search Result 70, Processing Time 0.025 seconds

Improvement of the Performance of the Supersonic Abrasive Blasting Nozzle (초음속 연마가공 노즐의 성능개선에 관한 연구)

  • Kwak, Ji-Young;Jeon, Ik-Jun;Park, Se-Eun;Lee, Yeol
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.15 no.2
    • /
    • pp.9-15
    • /
    • 2016
  • The dynamics of gas-particle flow from a supersonic abrasive blasting nozzle have been studied by 1-D analytical calculation, including wall friction effects inside the nozzle. The developed code in the present study shows a satisfactory agreement with the other study's results. By utilizing the code, the redesign and optimization of the inner contour of a commercial abrasive blasting nozzle were carried out, and it was found that the redesigned nozzle in the present study can produce faster particle velocities at the nozzle exit by up to 22% compared with the original commercial nozzle.

A Study on the Development of Low-Altitude and Long-Endurance Solar-Powered UAV from Korea Aerospace University (3) - Flight Test Results and Analysis of Solar Powered UAV - (한국항공대학교 저고도 장기체공 태양광 무인기 개발에 관한 연구 (3) - 태양광 무인기 비행실험 결과 및 분석 -)

  • Kim, Doyoung;Kim, Taerim;Jeong, Jaebaek;Park, Sanghyuk;Bae, Jae-Sung;Moon, Seokmin
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.50 no.7
    • /
    • pp.489-496
    • /
    • 2022
  • This paper introduces the system for KAU-SPUAV, which is designed and developed by Korea Aerospace University, and verifies its performance through flight test. Specification of two versions of KAU-SPUAV, avionics system, and Ground Control System (GCS) are introduced. Three missions are performed with suggested UAVs: LTE signal mapping, circumnavigation of Jeju island seashore, and long endurance flight. Each mission consists of long distance and long endurance flight which takes advantage of KAU-SPUAV. Research team of KAU-SPUAV confirmed its versatility through suggested flight data. Also based on flight results, the team found the potential of performance improvement of KAU-SPUAV.

A Study on the Development of Low-Altitude and Long-Endurance Solar-Powered UAV from Korea Aerospace University (2) - Flight Control and Guidance of Solar Powered UAV - (한국항공대학교 저고도 장기체공 태양광 무인기 개발에 관한 연구 (2) - 태양광 무인기 비행제어 및 유도항법 -)

  • Kim, Taerim;Kim, Doyoung;Jeong, Jaebaek;Moon, Seokmin;Kim, Yongrae;Bae, Jae-Sung;Park, Sanghyuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.50 no.7
    • /
    • pp.479-487
    • /
    • 2022
  • This paper presents the control and guidance algorithm of a KAU-SPUAV(Korea Aerospace University - Solar Powered Unmanned Aerial Vehicle) which is designed and developed in Korea Aerospace University. Aerodynamic coefficients are calculated using the vortex-lattice method and applied to the aircraft's six degrees of freedom equation. In addition, the thrust and torque coefficients of the propeller are calculated using the blade element theory. An altitude controller using thrust was used for longitudinal control of KAU-SPUAV to glide efficiently when it comes across the upwind. Also describes wind estimation technic for considering wind effect during flight. Finally, introduce some guidance laws for endurance, mission and coping with strong headwinds and autonomous landing.

Clinical study of the 15patients survived after acute paraquat intoxication (급성 파라콰드중독후 생존한 15예 환자의 임상적 고찰)

  • Kim Dong-Woung
    • Journal of Society of Preventive Korean Medicine
    • /
    • v.3 no.1
    • /
    • pp.36-36
    • /
    • 1999
  • From January 1994 to April 1997, there was 15 survivals who was admitted to the department of internal medicine, Wonkwang Oriental Medicine' Hospital in Cheun-ju, after ingestion of paraquat, and treated with Oriental and western medicine therapy. For the patients, I investigated clinical symptoms, gastroduodenoscopy, intake by oral and parenteral route, and output by urine and stool, serum ALP, AST. ALT, Bilirubin, BUN, Creatinine level and urine analysis. On admission day, the LFT level was as follows. The serum mean ALP, AST, ALT, Total Bilirubin and Direct Bilirubin was 10.05${\pm}$2.75 KAU, 66.67${\pm}$9.88 IU/L, 43.80${\pm}$7.74 IU/L, 1.89${\pm}$1.22 ㎎/dl and 1.10${\pm}$1.14 ㎎/dl respectively. After that day, administered Gamdutang and checked the mean LFT level regullary. Until the 3rd day, the mean ALP, AST, ALT, Total Bilirubin and Direct Bilirubin level was 11.0l${\pm}$3.16 KAU, 56.47${\pm}$7.19 IU/L, 59.00${\pm}$7.57 IU/L, 2.54${\pm}$1.78 ㎎/dl, 1.64${\pm}$1.59 ㎎/dl respectively. From 4th day to 7th day, the mean ALP; AST, ALT, Total Bilirubin and Direct Bilirubin level was 12.51${\pm}$3.49 KAU, 77.85${\pm}$7.17 IU/L, 58.00${\pm}$9.09 IU/L, 2.54${\pm}$1.97 ㎎/dl, and 1.80${\pm}$1.81 ㎎/dl respectively. From 8th day to 10th day, the mean ALP, AST, ALT, Total Bilirubin and Direct Bilirubin level was 12.43${\pm}$3.14 KAU, 41.13${\pm}$6.49 IU/L, 50.40${\pm}$7.17 IU/L, 1.66${\pm}$1.90 ㎎/dl and 1.14${\pm}$1.50 ㎎/dl respectively. From 11th day to 14th day, the mean ALP, AST, ALT, Total Bilirubin and Direct Bilirubin level was 12.30${\pm}$3.25 KAU, 31.07${\pm}$3.85 IU/L, 43.33${\pm}$5.49 IU/L, 1.62${\pm}$1.95 ㎎/dl, 1.17${\pm}$1.71 ㎎/dl respectvely. On admission day, the mean RFT level as follows. Serum BUN and Creatinine level was 28.73${\pm}$5.19 ㎎/dl and 1.82${\pm}$1.27 ㎎/dl respectively. After that day, administered Gamdutang and checked the mean RFT level regullary. Until the 3rd day, the mean BUN and Creatinine level was 32.12${\pm}$5.65 ㎎/dl and 2.31${\pm}$0.45 ㎎/dl respectively. From 4th day to 7th day, the mean BUN and Creatinine level was 31.07${\pm}$5.47 ㎎/dl and 1.92${\pm}$0.79 ㎎/dl respectively. From 7th day to 10th day, the mean BUN and Creatinine level was 17.47${\pm}$3.57 ㎎/dl and 1.33${\pm}$0.59 ㎎/dl respectively. From 11th day to 14th day, the mean BUN and Creatinine level was 11,93${\pm}$3.16 ㎎/dl, 1.27${\pm}$0.38 ㎎/dl respectively.

Wind tunnel section model study of aeroelastic performance for Ting Kau Bridge Deck

  • Brownjohn, James Mark William;Choi, Cheong Chuen
    • Wind and Structures
    • /
    • v.4 no.5
    • /
    • pp.367-382
    • /
    • 2001
  • Wind tunnel tests were conducted on a model of deck section from the Ting Kau cable stayed bridge. The purpose of the tests was to determine the set of aerodynamic derivatives conventionally used to describe the motion-induced forces arising from the wind flow, and to investigate the stability of the deck under different conditions of turbulence and angle of attack. The study shows that except for large negative angles of attack the deck section itself is stable up to a high wind speed, and that when instability does occur it is essentially a single degree of freedom (torsional) flutter.

High throughput sorting(HTS) system using a cantilever-type electrode array (캔틸레버(Cantilever) 형태의 전극 어레이(array)를 이용한고속 분리 시스템)

  • Lee, Jung-Hun;Kim, Young-Ho;Kim, Young-Geun;Kim, Byung-Kyu
    • Journal of Sensor Science and Technology
    • /
    • v.19 no.2
    • /
    • pp.112-117
    • /
    • 2010
  • A high-throughput sorting (HTS) system has been designed to separate target particles using a negative dielectrophoretic (n-DEP) force. The system consists of a meso-sized channel and a cantilever-type electrode(CE) array designed to separate a large number of target particles by discerning subtle difference of weight and dielectric material property of the particles. Using the polystyrene beads with various sizes of 10, 25 and $50{\mu}m$, the developed system exhibits high-throughput sorting of about 200 beads/sec and more than 80 % of separation efficiency.

Development of Multi-functional Centerless Grinding System with 600 mm Wide Grinding Wheels (600 mm 급 다기능 광폭 센터리스 연삭시스템 개발)

  • Oh, Jung Soo;Cho, Chang Rae;Tsukishima, Hidehiro;Cho, Soon Joo;Park, Chung Hong;Oh, Jeong Seok;Whang, In Bum;Lee, Won Jae;Kim, Seok Il
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.30 no.11
    • /
    • pp.1129-1137
    • /
    • 2013
  • We report a centerless grinding machine which can perform multi-function with 600 mm wide grinding wheels. By increasing manufacturing area, long workpiece such as camshaft and steering shaft, is allowed to grind more quickly, compared with cylindrical grinding system. In this paper, the design of centerless grinding machine puts emphasis on symmetry to exploit the thermal stability. Results of finite element analysis shows that the difference of the structural deflection in the front and rear guideways is less than $1.5{\mu}m$ due to symmetric design. The difference is less than $3.0{\mu}m$, even though the thermal deformation is considered. According to the performance evaluation, the radial error motion of the G/W spindle, which is measured by applying Donaldson Ball Reversal, is about 1.1${\mu}m$. The yaw error of the G/W slide is improved from 2.1 arcsec to 0.5 arcsec by readjusting the slide preload and ball screw.

Characteristics of Polymetallic Occurrence in Kau Loc Area within Northern Vietnam: Preliminary Study (베트남 북부 카우록 다중금속 산출지의 특성: 예비연구)

  • Heo, Chul-Ho;Chi, Se-Jung;Park, Sung-Won;Lee, Jae-Ho
    • Economic and Environmental Geology
    • /
    • v.44 no.5
    • /
    • pp.345-357
    • /
    • 2011
  • It was carried out to the survey on the lead-zinc and tungsten occurrences in the Kau Loc mineralized belt within northern Vietnam. The lead-zinc occurrence bear the ore body parallel to the bedding of limestone formation. Assuming the surface grade and geological reserve, Pb+Zn deposit is estimated to the small to medium-sized ore deposit. On the other hand, considering the distribution of small-scale stock intruding the Devonian limestone, it is thought that the tungsten occurrence has the proper geological conditions anticipating the presence of skarn mineralization. However, there is no evidence to recognize economic feasibility in the present situation because of the absence of detailed geology and ore deposit survey on the tungsten occurrence.

Effects of Glass Texturing Structure on the Module Efficiency of Heterojunction Silicon Solar Cells

  • Park, Hyeongsik;Lee, Yoo Jeong;Shin, Myunghun;Lee, Youn-Jung;Lee, Jaesung;Park, Changkyun;Yi, Junsin
    • Current Photovoltaic Research
    • /
    • v.6 no.4
    • /
    • pp.102-108
    • /
    • 2018
  • A glass-texturing technique was developed for photovoltaic (PV) module cover glass; periodic honeycomb textures were formed by using a conventional lithography technique and diluted hydrogen fluoride etching solutions. The etching conditions were optimized for three different types of textured structures. In contrast to a flat glass substrate, the textured glasses were structured with etched average surface angles of $31-57^{\circ}$, and large aspect ratios of 0.17-0.47; by using a finite difference time-domain simulation, we show that these textured surfaces increase the amount of scattered light and reduce reflectance on the glass surface. In addition, the optical transmittance of the textured glass was markedly improved by up to 95% for wavelengths ranging from 400 to 1100 nm. Furthermore, applying the textured structures to the cover glass of the PV module with heterojunction with intrinsic thin-layer crystalline silicon solar cells resulted in improvements in the short-circuit current density and module efficiency from 39 to $40.2mA/cm^2$ and from 21.65% to 22.41%, respectively. Considering these results, the proposed method has the potential to further strengthen the industrial and technical competitiveness of crystalline silicon solar cells.

Design of the Active Optical Compensation Movements for Image Stabilization of Small Satellite (소형 위성 영상안정화를 위한 능동형 광학 보정장치 설계)

  • Hwang, Jai Hyuk;Yang, Ji Youn;Park, Jean Ho;Jo, Jeong Bin;Kang, Myoung Soo;Bae, Jae Sung
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.43 no.5
    • /
    • pp.472-478
    • /
    • 2015
  • This paper describes the design of the active optical compensation movements(at focal plane, secondary mirror) for the image stabilization of a small satellite camera. The movements can correct optical misalignment on-line and directly compensate vibration disturbances in the focal plane. Since the devices are installed inside the space camera, it has an remarkable advantage to deal with the structural deformation of a space camera effectively. In this paper, the requirements of the active optical compensation movements for 1m GSD small satellite camera have been analyzed. Based on the established requirements, the design of the active compensation movements have been conducted. The designed active optical compensation system can control 5 axes movements independently to compensate micro-vibration disturbances in the focal plane and to refocus the optical misaligned satellite camera.