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TAEJOO KIM,김종록,CHEULMUU SIM,SUNGHO LEE,YOUNGJIN SON,MOOHWAN KIM 한국원자력학회 2009 Nuclear Engineering and Technology Vol.41 No.1
In this investigation, we prepared a 1 and 3-parallel serpentine single PEMFC, which has an active area of 100 cm2 and a flow channel cross section of 1x1mm. Distribution and transport of water in a non-operating PEMFC were observed by varying flow types and the flow rates (250, 400, and 850 cc/min). This investigation was performed at the neutron imaging facility at the COld Neutron RAdiography facility (CONRAD), HMI, Germany of which the collimation ratio and neutron fluence rate are 250, 1 106 n/s/cm2, respectively. The neutron image was continuously recorded by a scintillator and lens- CCD coupled detector system every 10 seconds. It has been observed that although the distilled water was supplied into the cathode channel only, the neutron image showed a water movement from the cathode to the anode channel. The water at the cathode channel was completely discharged as soon as the pressurized air was supplied. But the water at the anode channel was not easily removed by the pressurized air except for the 3-parallel serpentine type with 850 cc/min of air flow rate. Moreover, the water at the MEA wasn’t removed for any of the cases.
Taejoo Roh(노태주),Sangwon Seo(서상원) 한국산업경영시스템학회 2017 한국산업경영시스템학회지 Vol.40 No.3
Defense industries which require high reliability need an optimized quality management system with well-planned implementation. And the government should examine the overall status of defense industries, then establish practical policies with a proper support plan in required areas to upgrade the quality management level of manufacturers. Thus, DTaQ developed the model for 2 years from 2014, which specialized in quality management level analysis for defense industries. And a survey has been undertaken with that model by DTaQ and Korea Research Center in 2016. The surveyed companies randomly sampled among those which have more than 30 employees and delivery history over past 3 years, and finally 106 defense industries were selected. This paper present survey method and indexes for survey of defense industry quality management level. The survey was conducted in the order of planning, data collection and data processing, and the validity and reliability of the data were verified to increase objectivity of survey results. The survey contents mainly consist of system quality and management quality. System quality includes Product Development Management, Production Operation Management, supply chain quality management, Safety & Environment Management and Reliability Management, on the other hand, management quality includes Strategic Leadership, Human Resource Management, Customer Market Management and Information & Knowledge Management. Thus this proposes the current overall quality management status of the 106 defense industries and shows level differences by company sizes and manufacturing sectors based on the result of survey. Specifically, this paper enables to track the areas which need prompt government support with the policy directions to make quality management level higher. Therefore, it is expected that this can be used as reference data in establishing quality policies for military supplies in the future.
프롭 로터 천이비행 조건 전달행렬 생성을 위한 매개변수 연구
김태주(Taejoo Kim),윤병일(Byung Il Yun) 한국소음진동공학회 2024 한국소음진동공학회 논문집 Vol.34 No.2
A parameter study was conducted to calculate the hub load transfer matrix (T-matrix) for each transient flight condition in order to reduce the hub vibration load through individual blade control (IBC) under transient flight conditions for a 5-blade tilt-prop rotor capable of tilt operation. First, the prop-rotor operating conditions for each transient flight condition were derived. For this purpose, a total of 9 maneuvering conditions were identified, and the tilt angle, forward flight speed, and prop rotor rotation speed for each condition were derived. Then, the parameters to be adjusted were selected using the IBC formula, and the hub load calculation results according to changes in each parameter were analyzed. In this case, the IBC operating frequency, amplitude, and phase angle were selected as parameters. Based on these results, an IBC parameter study was conducted for a total of 7 transient flight conditions, and the hub normal load for each condition was derived. The results of this study can be used to analyze the variation of the hub load according to the variation of the IBC input and generate a hub load transfer matrix for each transient flight condition. Additionally, active vibration control research will be conducted under UAM(urban air mobility) transient flight conditions using the generated hub load transfer matrix.
대면 구조 유전체 장벽 방전 플라즈마의 X-Band 내 RCS 저감 효과
오태주(Taejoo Oh),조창석(Changseok Cho),안욱현(Wookhyun Ahn),김상인(Sangin Kim),육종관(Jong-Gwan Yook),이장재(Jangjae Lee),유신재(Shinjae You),임진우(Jinwoo Yim),하정제(Jungje Ha),배지훈(Gihun Bae),유흥철(Heung Cheol You),이용식(Yongshi 한국전자파학회 2020 한국전자파학회논문지 Vol.31 No.12
본 논문에서는 RCS 저감을 위한 대면 구조 유전체 장벽 방전(DBD: dielectric-barrier-discharge) 플라즈마 발생기를 제안한다. 두께가 0.254 mm 두께인 Ro4350b 기판 위, 아랫면에 16×0.5 ㎠ 크기의 도체가 5 mm의 간격을 두고 서로 마주보고 있는 구조로 타겟에 부착시킴으로써 레이다 단면적(RCS)을 감소시킬 수 있다. 전극이 수직으로 놓일 수밖에 없는 평행판 커패시터 구조의 기존 발생기와 달리 제안한 발생기는 전극이 레이다 신호의 입사 방향과 평행하게 놓이므로 목표물의 RCS에 영향을 최소화하여 플라즈마의 효과를 극대화할 수 있다. 제안하는 대면 구조 발생기를 42층으로 적층한 뒤 20×20 ㎠ 크기의 구리 평판 목표물에 적용하여 X-band 내에서 최대 3.2 dB의 RCS 감소 효과가 있는 것을 실험적으로 검증하였다. 이를 통해 제안하는 플라즈마 발생기의 구조적인 장점과 더불어 RCS 저감 효과 측면에서도 그 우수한 성능을 확인하였다. A dielectric barrier discharge (DBD) plasma generator with a face-to-face multilayer structure for radar cross section (RCS) reduction is designed. The generator includes two electrodes of 16×0.5 ㎠ size, facing each other. Because the electrodes are on the plane that is parallel to the direction of the incident wave, the effect of the generator on the RCS of the target is significantly reduced, particularly when compared to conventional parallel plate-type generators. This simplifies the design procedure for the DBD generator and maximizes the effect of the plasma on RCS reduction. For experimental verification, 42 layers of the proposed generator with a distance of 5 mm between the two electrodes are stacked to reduce the RCS of a 20×20 ㎠-sized copper plate. Experimental results demonstrated a reduction of approximately 3.2 dB in the RCS in the X-band.
김태주(Taejoo Kim),조진연(Jin Yeon Cho) 한국항공우주학회 2018 韓國航空宇宙學會誌 Vol.46 No.10
최대 이륙중량 kg에 최대 순항속도가 km/h이고 수직이착륙이 가능한 쿼드 틸트 프롭로터 무인기에 적용한 프롭-블레이드 단면 설계를 수행하였다. 먼저 프롭-블레이드 단면 설계수행을 위한 설계 프로세스를 수립하고 단면 설계에 필요한 요구도를 식별하였으며 식별된 요구도 만족을 위한 단면 설계를 수행하였다. 단면 설계 결과를 분석하기 위하여 유한요소 단면해석 프로그램을 활용하여 인장/굽힘/뒤틀림 강성 및 단위길이 당 중량, 탄성 축 등을 포함한 주요설계 인자들을 도출하였으며, 이 과정에서 프롭-블레이드의 설계 붕량을 예측하였다. 그리고 도출된 설계 인자들을 로터시스템 통합 해석 프로그램에 적용하여 프롭-블레이드 운영 환경에서의 동적 안정성을 분석하였으며, 로터시스템 통합 해석 프로그램을 통해 분석된 프롭-블레이드 하중을 활용하여 2차원 단면 구조 해석을 수행하여 프롭-블레이드 구조 안전성을 확인하였다. 이러한 단면 설계/해석 과정에서 설계 요구도를 만족시키지 못하거나 다른 구성품에 부정적 영향을 준 설계 결과에 대해서는 설계 변경을 수행하였으며, 이를 통해 요구도를 만족시켰다. 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.