• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.48-53
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• 2014

Rocket, held using the CCA for the mission, a plurality of recording devices, and navigation equipment. In case of a projectile which is entered the water after fired into the air, after performing stages and fairing separated in flight to enter the underwater. It is caused by the explosion of gunpowder mainly, vibration phenomenon of a large transition is induced structurally very, also on entering the water, have a significant shock structurally separated. If shock is transmitted directly to the CCA through the body, it can be caused malfunction of payloads, resulting in failure of the mission of the projectile. In order to ensure the stability against shock, in this paper, Calculating a target resonacne frequency of the CCA, and verified through modal test and analysis. Maximum acceleration position of CCA is checked by SRS analysis. In addition, effectiveness of shock isolation system through shock analysis.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.97-102
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• 2004

Propulsion System provides the required velocity change impulse for orbit transfer from parking orbit to mission orbit and three-axis vehicle attitude control impulse. KOMPSAT-2 propulsion system(PS) is an all-welded, monopropellant hydrazine system. The PS consists of the subassemblies and components such as Thrusters, Propellant Tank, Pressure Transducer, Propellant Filter, Latching Isolation Valves, Fill/Drain Valves, interconnecting propellant line assembly, and thermal hardwares for operation-environment control of the PS. This paper summarizes a development process of the liquid propulsion system from the design engineering up to the test and evaluation.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1564-1565
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• 2006

현재 전세계적으로 170kV급 이하의 초고압 지중케이블 접속함으로 기존의 현장몰드방식의 TMJ(Tape Molded Joint)와 부품조립방식의 PJ(Prefabricated Joint)보다 조립시간이 짧고 작업자의 숙련도가 높지 않아 경제적이며, 유지보수에 장점을 가진 고무몰드 접속함(PMJ)이 채용되고 있으며, 이러한 추세는 적용 전압급이 점차 상승하면서 230kV급까지 그 비중이 늘어나고 있는 경향을 보이고 있다. 당사에서는 이러한 추세에 발맞추어 154kV급 고무몰드접속함의 개발 당시의 Silicone의 기초물성시험 DATA 획득, 고무몰드 UNIT 및 금형 설계 기술 확립과 접속 공법 개발의 경험을 바탕으로 230kV급 고무몰드접속함의 개발에 성공하였다.

• International Journal of Highway Engineering
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• v.5 no.1 s.15
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• pp.35-45
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• 2003

This paper presents a theoretical approach for estimation of CBR-value of subbase course and subgrade using a portable pavement dynamic cone penetrometer(PDCP). The PDCP used in this paper was based on a design from South Africa and extensive studies by Kleyn(1982) and more recently by Liveneh and Ishai(1987) and Chua(1988). To date, California Bearing Ratio[CBR] value was studied mainly for application of pavement structural design. This study was initiated to develop a method of obtaining the in situ CBR-values of subbase and subgrade for the structural evaluation of pavements in the swift and inexpensive manner. PDCP tests were implemented at 20 different kinds of soil samples in the lab and test results were analysed by a theoretical approach introduced. The procedure presented provides acceptable and promising results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.246-254
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• 2016

Thick-shell welding for super-sized oil storage tanks is currently done manually, which causes deterioration in quality and a lack of uniformity due to frequent rewelding. The limitations of the external environment must also be considered for manual welding. This paper describes the development of a carriage system for automatic vertical welding to increase reliability, reduce cost, and enhance productivity. The system consists of a welding platform, carriage device, and control unit, which were conceptually designed according to design specifications and manufactured with modular parts. In addition, the structure was analyzed for safety and to predict design problems in advance, and the results are reflected in reviewing the design. To evaluate the performance of the system, a tensile test, bending test, and weld time test were carried out, and the results were satisfactory. The time required for automatic weld was greatly improved by more than 87%, compared to the manual welding time.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.9
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• pp.782-789
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• 2018

Multi-Function Display (MFD) of Korean Utility Helicopter (KUH) displays image information(navigation, flight, topographical and maintenance information) delivered from Mission Computer (MC) during flight operation. The abnormal display of MFD such as flickering phenomenon was identified in the system development. It was solved by improving the shielding performance of the DVI cable and changing the DVI cable installation path at the first mass production. However, it was occurred again when the aircraft was operated for one or two years after delivery. It was also identified in the evaluation process of the derivative helicopters. Therefore, a comprehensive review of the aircraft system level has been performed to solve the problem of MFD malfunction at first and then a design improvement plan was derived by improving the DVI cable. In this paper, the causes of MFD anomalies are analyzed and also the process of design improvement are summarized. The validity of the improvement has been verified through the DVI cable assembly comparison test, SIL/ground/flight test.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.38 no.7
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• pp.29-38
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• 2009

지난 20년간 급속한 발전을 통하여 회전 블레이드의 직경이 126 m, 나셀까지의 높이가 약 130 m에 이르는 6,000 kW의 용량을 가지는 풍력발전기가 개발되었다. 세계적으로 풍력발전의 필요성과 중요성이 인식되어 2008년 현재 약 120,000 MW의 설치 용량을 기록하고 있다. 풍력터빈(wind turbine)과 그 부품의 기계적인 성능평가의 종류와 방법은 많은 사람들의 관심인 것으로 판단한다. 우선 풍력터빈을 구성하는 주요 핵심부품은 블레이드, 증속장치, 발전기 등이며, 세부 구성 부품으로 허브, 핏치와 요베어링, 주축베어링, 타워 등이 있다. 주요핵심 부품인 블레이드, 증속기, 발전기 등의 성능평가가 중요한 이슈이다. 또한 모든 구성품을 조립하여 초기의 설계사양에 따라서 제조되고 최종성능이 발휘되는지 여부를 현장시험을 통하여 성능평가과정을 거치게 되는데 이 과정은 풍력터빈의 성능평가라고 하며 주요 평가대상은 출력성능(power performance), 소음(noise), 하중(load), 전력품질(power quality) 등 4가지 항목을 집중적으로 측정하여 개발된 풍력터빈의 전반적인 성능을 평가하게 된다. 본 투고에서는 핵심부품인 블레이드, 증속기, 발전기에 대한 시험기술과 풍력터빈의 성능평가 항목인 4개 측정 항목에 대하여 기술하였다.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.176-186
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• 2008

As determined single coaxial cable for the interface between satellite and ground station in COMS RF compatibility test, RF supporting unit was required to allow signals in different frequency-band to be exchanged in the single coaxial cable. In addition, the path loss between satellite and ground station in normal operation should be simulated through two RF supporting units connected to the ends of single coaxial cable. As an effort to design RF supporting unit, level diagram was firstly conducted on the basis of measured data for each element. From the level diagram, it was found that single coaxial cable connected with two RF supporting units properly represented the path loss between satellite and ground station After RF supporting unit was integrated on aluminum plate, it was tested that input signal level at each test cap linked with MODCS and TC&R was tunable within the required dynamic range. RF supporting unit, now completely integrated, will be applied in the upcoming COMS RF compatibility test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.947-952
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• 2010

Components such as pressure vessel, hydraulic hose assembly, accumulator, hydraulic cylinder, hydraulic valve, pipe, etc., are tested under the impulse-pressure conditions prescribed in ISO and SAE standards. The impulse pressure test machine needs to have a high pressure, a precise control system and a long life. It should satisfy the requirements for fabrication of the impulse tester to generate ultra high pressure in the hydraulic system. In the impulse tester, a servo-valve control system is adopted; although the control application is convenient, it is expensive owing to the cost of developing the system. The type of the control system determines the pressure wave, which affects the components that are tested. In this study, the manufacturing process and the intensifier system design related to the flow, pressure, and the increasing rate of pressure are investigated. The results indicate the ultra high pressure waves in the system.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.817-827
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• 2008

The seismic performance of a column splice fabricated with PJP (partial joint penetration) welds for special moment frames was experimentally evaluated in this study. The steel materials that were used for the specimens included SHN490 and SN490 steel, or the newly developed structural steel for seismic application. Fabricating the column splice with PJP welds is highly attractive from the perspective of reducing the welding cost and the construction time. PJP welds in column splices are viewed apprehensively, however, because several tests have shown that PJP welds in thick members tend to become brittle under tensile loads. The column splices in this testing program were designed for the expected plastic moment of the column that current seismic codes typically require. The design strength of partial-penetration welded joints was determined according to the 2005 AISC-LRFD Specification. Three-point loading was applied monotonically, using a universal testing machine, such thatthe column splice joints were subjected to pure tension. The test results showed that the PJP welded splices, if designed properly, can develop a strength exceeding that of the actual plastic moment of the column. The specimen made of the SM490 rolled section, however, showed a brittle fracture at the splice soon after achieving the actual plastic moment of the column. The tensile coupon test results also showed that the material properties of SM490 steel are more unpredictable. Overall, although the test data are limited, the SHN490 and SN490 steel specimens showed a superior and reliable performance.