• 터널과지하공간
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• 제34권2호
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• pp.89-103
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• 2024

처분 환경에서는 혐기성 부식, 방사선 분해, 미생물 분해와 같은 다양한 원인으로 처분용기와 완충재의 경계면에서 기체가 발생할 수 있다. 기체의 발생 속도가 완충재 내부에서의 확산 속도보다 빠를 경우, 완충재 내부에 기체가 압축되어 공극 압력이 증가함으로써 완충재의 물리적 손상을 유발할 수 있다. 특히 이때 발생한 균열을 통해 기체돌파현상이라 불리는 급격한 기체 이동 현상과 함께 방사성 핵종이 누출될 가능성이 있다. 따라서 처분 시스템의 안전성 평가를 위해서는 이러한 기체 발생 및 이동 현상에 대한 이해가 필수적이다. 이 연구에는 완충재 내 기체 이동 현상 규명을 위한 시험 장치를 문헌 연구를 통해 구축하고, 이를 활용하여 한국형 처분 시스템의 완충재 후보 물질 중 하나인 Bentonile WRK (Clariant Ltd.) 분말로 제작한 압축 시료에 대한 기체 주입 시험을 수행하였다. 시험 결과, 완충재 내 기체돌파현상 발생 지점에서 일반적으로 관측되는 특성인 응력 및 압력의 급격한 상승 경향이 뚜렷하게 관찰되었다. 또한 완충재 팽윤으로 기인한 응력의 범위는 4.7~9.1 MPa이었으며, 기체 유입 압력으로 간주할 수 있는 기체돌파현상 발생 시의 압력은 약 7.8 MPa로 확인되었다. 구축된 장치는 향후 완충재의 초기 물성 및 기체 주입 실험 초기 조건에 대한 데이터베이스 구축을 위한 다양한 실험에 활용할 수 있을 것으로 기대된다.

• 한국항공우주학회지
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• 제31권10호
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• pp.60-65
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• 2003

회전분무시스템을 적용한 가스터빈연소기의 점화특성을 연구하기 위한 실험적 연구를 수행하였다. 연료분사는 연료를 회전연료노즐의 내측에 공급한 후, 고속모터로 회전하는 연료노즐에서 발생하는 원심력을 이용하여 분사되는 방식을 이용하였다. 실물크기의 연소기 및 시험리그를 제작하여 한국항공우주연구원의 연소시험설비를 이용하여 대기압 조건에서 연소시험을 수행하였다. 시험결과 이 연소기의 점화성능은 연료노즐의 회전속도를 증가하거나 감속할 경우 연소가스의 온도가 급격하게 변화되는 특성이 있음을 알 수 있었다.

• 한국자동차공학회논문집
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• 제23권4호
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• pp.410-419
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• 2015

In this study, the roadability, fuel economy and emission characteristics were evaluated for a natural gas converted vehicle. The results are as follows; Not only the shortage of power was observed in stall test, but also large deterioration of acceleration performance was exposed in roadability. Compared to the original LPG system, the acceleration is 76% in start acceleration and 45 ~ 65% in overtaking acceleration, especially the decline became larger when air conditioner is at work. Furthermore, because the mapping data, which controls the injection depending on driving condition, do not match up with injection system, the failure of air-fuel ratio feedback control occurs resulting from the large gap between the required and the really supplied amount of fuel. This failure cause the exhaust gas to emit without catalytic conversion and the fuel economy based on the fuel heat value to get worse 22% in the mode test and 16% in road test respectively. In addition, the existing injection system does not secure enough fuel at the starting so that it may lead to the fail of clod start, the deterioration of hot start and inharmonic of engine at the idle after start.

• 한국자동차공학회논문집
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• 제5권5호
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• pp.97-103
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• 1997

Effects of fuel injection timing on the lean misfire limit of a sequential MPI SI engine has been investigated. To investigate the interaction of injection timing and intake flow characteristics, so called axial stratification phenomena, 4 kinds of different intake swirl port of the same combustion chamber geometry have been teated in a single cylinder engine test bench. And 2 kinds of fuel, gasoline and compressed natural gas(CNG), were used to see the effect of liquid fuel vaporization. Result shows that combination of port swirl and injection timing governs the lean misfire limit and lean misfire limit envelopes remain almost the same for a given ratio regardless of engine speed. It is also found that two phase flow has some effects on lean misfire limit.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.496-501
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• 2003

Computational study is performed to understand the fluidic thrust vectoring control of an axisymmetric nozzle, in which secondary gas injection is made in the divergent section of the nozzle. The nozzle has a design Mach number of 2.0, and the operation pressure ratio is varied to obtain the different flow features in the nozzle flow. The injection flow rate is varied by means of the injection port pressure. Test conditions are in the range of the nozzle pressure ratio from 3.0 to 8.26 and the injection pressure ratio from 0 to 1.0. The present computational results show that, for a given nozzle pressure ratio, an increase of the injection pressure ratio produces increased thrust vector angle, but decreases the thrust efficiency.

• 한국자동차공학회논문집
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• 제22권5호
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• pp.35-43
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• 2014

The automobile industry requires technological innovations to reduce fuel consumption with the public interest in environmental conservation in recent years. Thus, the hybrid system is applied not only to passenger cars but also commercial vehicles. The purpose of this paper is to develop engine ECU_ILS to develop commercial hybrid vehicles. In order to develop the engine and vehicle, the dynamometer and exhaust gas analyzer is needed. However, a lot of time and cost are required. In contrast, the model-based development environment that can be applied to a variety of test conditions can reduce development time. Therefore, a HILS system environment that can consider the behavior of actual vehicles for evaluation of the control logic, fuel consumption and exhaust gas is required. This engine ECU_ILS system was developed in this study, can analyze parameter such as the fuel injection rate, fuel injection time, fuel consumption and exhaust gas like the actual vehicle test using map data. Also, this system is expected to be able to analyze the characteristic of vehicle behavior and the development of peripheral device in relation to engine and vehicles. This HILS system can be used to develop control strategies of commercial hybrid vehicle systems in the future.

• 한국항공우주학회지
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• 제33권12호
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• pp.68-75
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• 2005

주유동 기체의 물리적 특성이 초음속 이젝터 성능에 미치는 영향에 관한 연구를 수행하였다. 기체의 분자량과 정압 비열 변화에 따른 성능 변화에 관한 연구는 축대칭 환형 분사 초음속 이젝터를 사용하였다. 주유동 기체로는 공기, $CO_{2}$, Ar, $C_{3}H_{8}$, $CCl_{2}F_{2}$를 사용하였다. 주유동 기체의 분자량과 정압 비열이 증가함에 따라 일정 주유동 압력에 대한 부유동 압력은 증가하였고 이러한 경향은 몰비열이나 비열비의 형태로 통합되어 확인되었다.

• 한국자동차공학회논문집
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• 제20권5호
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• pp.13-18
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• 2012

This research is about the exhaust gas and driving performance test which are for CNG-Diesel dual fuel engine. The CNG-Diesel dual fuel engine converted from 2500cc diesel has two steps of injection systems; small amount of diesel is injected to mixture CNG in cylinder to ignite before CNG is injected into each intake manifold to form mixture. The amounts of output power and emission in duel fuel consumption were measured by engine dynamometer and exhaust gas analyzer. Over 90% of diesel consumption reduction, similar driving performance to current diesel engine and reduced emission on $CO_2$ and PM, respectively, were indicated through the measurements. The two steps of system were applied to vehicle to investigate exhaust gas characteristics and driving performance via NEDC mode and real driving test. Additional oxidation catalyst was applied to reduce emission on the test vehicle and the NEDC mode test showed the reduction of Co, $CO_2$, Pm and THC.

• Nuclear Engineering and Technology
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• 제45권3호
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• pp.347-360
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• 2013

This paper presents an experimental investigation of the small-break loss-of-coolant accident (SBLOCA) and the loss-of-feedwater accident (LOFW) in a scaled integral test facility of REX-10. REX-10 is a small integral-type PWR in which the coolant flow is driven by natural circulation, and the RCS is pressurized by the steam-gas pressurizer. The postulated accidents of REX-10 include the system depressurization initiated by the break of a nitrogen injection line connected to the steam-gas pressurizer and the complete loss of normal feedwater flow by the malfunction of control systems. The integral effect tests on SBLOCA and LOFW are conducted at the REX-10 Test Facility (RTF), a full-height full-pressure facility with reduced power by 1/50. The SBLOCA experiment is initiated by opening a flow passage out of the pressurizer vessel, and the LOFW experiment begins with the termination of the feedwater supply into the helical-coil steam generator. The experimental results reveal that the RTF can assure sufficient cooldown capability with the simulated PRHRS flow during these DBAs. In particular, the RTF exhibits faster pressurization during the LOFW test when employing the steam-gas pressurizer than the steam pressurizer. This experimental study can provide unique data to validate the thermal-hydraulic analysis code for REX-10.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.54-59
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• 2004

The goal of this research is to confirm reliable durability and evaluate the engine performance of the current aluminum alloy piston and the newly developed steel forging piston. For such purpose, the test environment was built with 2.91 target engine mounted on the engine dynamometer and additional exhaust gas analysis system. Using the test environment, engine performance test was conducted, and durability test was also conducted using a dedicated piston durability test equipment for 400,000 km. As a result of the experiment, similar durability was appeared for both aluminum piston and steel piston, and the engine output power and torque are slightly reduced because of $158\%$ heavier weight of the steel piston compare to the aluminum alloy piston.