• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.165.1-165.1
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• 2011

In this paper, it is intended to study about deferences of design and operation properties between large and small hydro-power house's turbine which type is reaction. In generally, turbine of large hydro-power has a more safe and effective energy output mechanisms than small hydro-power's because the turbine of small hydro-power is more sensitive to hydraulic losses. But, it is more effective for the all energy market to improve the capability and efficiency of small hydro-power in the present status of increasing construction of small hydro-power than large hydro-power. Therefore, we intend to investigate and introduce the way to enhance the efficiencies of reaction turbine adopted to small hydro-power.

• Fire Science and Engineering
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• v.26 no.3
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• pp.91-99
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• 2012

Fatal injuries and deaths have occurred resulting from the operation or disassembling of a powder extinguishers in Korea. If a rusted powder extinguisher is exploded during operation or disassembling, it rises to the air like a rocket and hits a head, chest, or neck part of an operator, resulting in his (her) death or injury. In this study examines the explosion accident cases of a powder fire extinguisher and analyzes their causes, reactions to explosion, and precautionary measures. And in this paper suggests 1) no using of old fire extinguishers in fire drill or education, 2) education and public information on danger of old fire extinguishers, 3) indication of explosion danger to cartridge-type dry chemical powder fire extinguishers had already placed to buildings etc., 4) obligatory indication of durable years on fire extinguishers, 5) examination for introduction of system that do hydraulic pressure test about fire extinguishers that given period past, 6) construction of system that reclaim old fire extinguishers, 7) construction of system that recycle or reuse old fire extinguishers, and 8) operation of help desk related to old fire extinguishers as precautionary measure of fire extinguisher explosion accidents.

• KASI NEWSLETTER
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• s.48
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• pp.1-8
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• 2005

신년사/ 천문연 영문 명칭 변경/ 한국우주전파관측망(KVN) 기공식/ "04년도 실적평가 및 "05년도 선정평가 공개발표회/ 박상대 이사장 UST, 특별강좌/ 박상대 이사장, 기초연 차세대 연구기반동 기공식 축사/ 조직개편/ 2005 역서, 천문력 발행/ 2004년 동계 교원 천문 연수 실시/ 한-일 VLBI 연구협력을 위한 공동 모임/ 과학기술인공제회 회원 가입신청/ 직원동정/ 학회동정/ 콜로키움/ 일본의 적외선 우주망원경 ASTRO-F/ 2004 천문학.우주과학 및 관련기술에 대한 한일 공동강의/ 레몬산천문대 원격관측 시연회 및 현판식/ 새로 발견된 5개의 소행성에 한국의 과학기술자 이름 헌정/ FIMS이용, 세계최초 돛자리초신성 전체 영상관측/ 크리미아천문대와 공동연구 협정 체결/ 천문 계산용 고성능 PC 클러스터 구축/ 중앙전파관리소와 우주전파기술 교류에 관한 협약 체결/ 세종대학교와 망원경 운영 협정서 체결/ 일본 우주과학연구본부와 상호협약서 체결/ 연구원 창립 30주년 기념식 거행

• Journal of the Korea Society for Simulation
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• v.24 no.4
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• pp.35-41
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• 2015

Recoil system for 40mm automatic gun is a device developed to absorb the shock of explosion. It is impossible to conduct pinpoint strike due to recoil if very high explosive shock, which is generated when an automatic gun fires shells, can't be absorbed. This study covers development and verification of analysis model for recoil system by utilizing a multi-domain software. The research process is as in the following. First, an analysis model is developed to verify damping characteristics through understanding of design intention. Second, environment which is identical to a field test is set up on analysis tool after putting explosive force that is measured through the test into the analysis model. Finally, the analysis model for recoil system using the multi-domain software is verified if it has effectiveness with a comparison between internal pressure of the recoil system along with displacement of gun barrel and the field test result.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.107-114
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• 2003

The effect of uncertainties caused by measured parameters, which are propagated to the uncertainty of total-to-total efficiency, are analyzed from a turbine performance test. The degree of reaction is 0.373 at the mean radius on a tested 3-D axial type turbine, and the performance test is conducted at the low pressure and cold temperature status. The uncertainty of turbine inlet and exit total pressure shows the strong propagation effect to the uncertainty of total-to-total efficiency. This means that a high precision pressure measuring system is required to reduce the uncertainty propagated by the pressure. In the uncertainty portion of each measured parameters to the uncertainty of total- to-total efficiency, the uncertainty by torque is the highest and the uncertainty by RPM is the lowest. In case of the total pressure, the effect of the uncertainty by torque is increased with the increasing RPM. The uncertainty of total pressure at the turbine exit is more important than that at the turbine exit.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.2
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• pp.24-31
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• 2001

An axial-type turbine design technology is developed. In order to design one-stage turbine, the preliminary design method is applied, and then design parameters are chosen after analyzing gas properties within the turbine passage using the streamline curvature method. Stator blade is designed using C4 profile, and rotor blade is designed using shape parameters. Stator is manufactured as an integral type and rotor is manufactured to be disassembled from the disc for changing blade incidence angle. The output power from the rotor is measured with various RPM and input power. Experimental results show that the maximum efficiency of turbine rotor is obtained on the design point, and the output power is proportionally decreased with the negative incidence angle even the test turbine is a reaction turbine. The efficiency of turbine rotor is decreased to 5% by $7.5^{\cire}$ negative incidence angle from the designed value.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.99-105
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• 2002

The performance test of an axial-type turbine is carried out with various axial gap distances between the stator and rotor. The turbine is operated at the low pressure and speed, and the degree of reaction is 0.373 at the mean radius. The axial-type turbine consists of ons-stage and 3-dimensional blades. The chord length of rotor is 28.2mm and mean diameter of turbine is 257.56mm. The power of turbo-blower for input power is 30kW and mass flow rate is $340m^3$/min at 290mmAq static-pressure. The RPM and output power are controlled by a dynamometer connected directly to the turbine shaft. The axial gap distances are changed from a quarter to three times of stator axial chord length, and performance curves are obtained with 9 different axial gaps. The efficiency varies about 8% of its peak value due to the variation of axial gap on the same non-dimensional mass flow rate and RPM, and experimental results show that the optimum axial gap is 1.6-1.9Cx.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.123-126
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• 2003

The uncertainties generated by measurement parameters are propagated to the uncertainty of total-to-total efficiency on an experiment. The effect of uncertainties’ propagation are analyzed through a turbine performance test. A tested 3-D axial type turbine has a 0.373 degree of reaction at the mean radius and the performance test is conducted at the low pressure and cold temperature status. The uncertainty of turbine inlet and exit total pressure shows the strong propagation effect to the uncertainty of total-to-total efficiency. This means that a high precision pressure measuring system is required to reduce the uncertainty propagated by the pressure. In the uncertainty portion of each measurement parameters to the uncertainty of total-to-total efficiency, the uncertainty by torque is the highest and the uncertainty by RPM is the lowest. In case of the total pressure, the effect of the uncertainty by torque is increased with the increasing RPM. The uncertainty of total pressure at the turbine exit shows more influence to the results than that at the turbine.

• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.179-190
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• 2008

The purpose of this study was to identify whether or not in one-leg vertical jump of each limb asymmetry between both sides is present and to identify how the discrepancies between both limbs affect two-leg jumping performance, that is bilateral deficit. We had 13 healthy subjects perform one-leg jump for both sides and two-leg countermovement jump. The result of biomechanical analysis showed significantly difference of 4-7% in net impulses and work output between dominant and non-dominant one-leg jump and bilateral deficit of 24% when sum of those of each one-leg jump was compared with two-leg jump. But asymmetry in lower extremity was not significantly correlated with bilateral deficit. Two-leg jump could be characterized by relatively short propulsion time, long propulsion distance and high joint angular velocity compared with one-leg jump. These factors seemed to contribute to decreased performance in two-leg jump. Furthermore bilateral deficit was attributed to lower activities of extensor muscles found in two-leg jump.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.115-122
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• 2020

This study aimed to improve the reliability of the assurance pressure of a gun barrel due to the difference between the US Standard and Korean Standard. In addition, the reliability was found to differ according to the maximum pressure of the Ammunition, so restrictions are expected. During the development of the new bullet, the maximum pressure of the bullet was approximately 3,000 psi higher than the assurance pressure of the gun barrel. To solve this problem, the reliability of the cannon was analyzed when the assurance pressure of the gun barrel increased. First of all, the technical data from overseas were reviewed to check for cases of increased assurance pressure, and tests were performed to determine if it could withstand high pressure through a verification firing test. Finally, the simulation analyzed the stability of the recoil buffer. The study found no abnormal results in all items, suggesting that an increase in the assurance pressure for a gun barrel was possible. This study is expected to be used as basic data for future reliability studies of similar equipment.