• Advances in materials Research
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• 제8권2호
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• pp.117-135
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• 2019

The lifetime of a gas turbine combustor is typically limited by the durability of its liner, the structure that encloses the high-temperature combustion products. The primary objective of the combustor thermal design process is to ensure that the liner temperatures do not exceed a maximum value set by material limits. Liner temperatures exceeding these limits hasten the onset of cracking which increase the frequency of unscheduled engine removals and cause the maintenance and repair costs of the engine to increase. Hot gas temperature prediction can be considered a preliminary step for combustor liner temperature prediction which can make a suitable view of combustion chamber conditions. In this study, the temperature distribution of ceramic panels for a V94.2 gas turbine combustor subjected to realistic operation conditions is presented using three-dimensional finite difference method. A simplified model of alumina ceramic is used to obtain the temperature distribution. The external thermal loads consist of convection and radiation heat transfers are considered that these loads are applied to flat segmented panel on hot side and forced convection cooling on the other side. First the temperatures of hot and cold sides of ceramic are calculated. Then, the thermal boundary conditions of all other ceramic sides are estimated by the field observations. Finally, the temperature distributions of ceramic panels for a V94.2 gas turbine combustor are computed by MATLAB software. The results show that the gas emissivity for diffusion mode is more than premix therefore the radiation heat flux and temperature will be more. The results of this work are validated by ANSYS and ABAQUS softwares. It is showed that there is a good agreement between all results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.336-338
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• 2006

Motorized retractors enhance the safety of passengers by removing the slack of webbing and by holding upright driving position. Reliability of a driving mechanism that includes one-way clutch between the driving motor and webbing is directly linked to the safety of passenger. In this research, conditions for locking one-way clutch and also conditions for sustaining locking are theoretically investigated. the operation of a motorized retractor under realistic conditions is simulated in order to validate the proposed retractor design.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(4)
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• pp.28-33
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• 1996

Wind-speed has much effect on the dispersion of the radioactive effluents released into the atmosphere. Accurate measurement of low wind-speeds is very important for the realistic assessment of radiation exposure. The objective of this study is to analyze the effects of different calm conditions on the radiation exposure due to the normal operation of a nuclear facility at KAERI (Korea Atomic Energy Research Institute) site. When calm condition is changed from 0.5 m/sec to 0.21 m/sec, the effects on radiation exposure show a distinct difference.

• ETRI Journal
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• 제40권5호
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• pp.570-581
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• 2018

This work analyzes the performance of implementable detectors for the multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) technique under specific and realistic operation system conditions, including antenna correlation and array configuration. A time-domain channel model was used to evaluate the system performance under realistic communication channel and system scenarios, including different channel correlation, modulation order, and antenna array configurations. Several MIMO-OFDM detectors were analyzed for the purpose of achieving high performance combined with high capacity systems and manageable computational complexity. Numerical Monte Carlo simulations demonstrate the channel selectivity effect, while the impact of the number of antennas, adoption of linear against heuristic-based detection schemes, and the spatial correlation effect under linear and planar antenna arrays are analyzed in the MIMO-OFDM context.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.582-588
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• 1993

A scheme of dynamic optimization for batch reactor his been developed and applied to a semi-batch esterification reactor. To obtain optimal operating conditions for the given semi-batch reactor system with complex reaction kinetic and process constraints, a general nonlinear programming solver and finite element techniques have been introduced. The optimization results for the complex reactor system have been compared with those of Kumar et al. [1984] to show better optimization performance. The proposed optimizing scheme has been applied to the free end time problem to obtain the realistic operating condition. The results can supply valuable information for economic operation of the given batch esterification reactor.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.199-204
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• 2000

A low temperature differential model stirling engine is manufactured, and its operation characteristics are measured and analyzed by SIMPLE analysis model, in which heat transfer processes are simply considered. The heat transfer coefficients between working fluid and heat sources in the analysis are estimated by comparing the P-V diagrams by experiment and by analysis. This result may be very useful for further design and manufacture of model Stilting engines as well as real engines because it provides a comparatively correct predictions of the operation conditions and power output. It will be also conveniently used as an educational material for mechanical engineering students because it can be a nice example of optimal design process to decide the phase angle and compression ratio of engine design with a simple but realistic simulation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.363-368
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• 2002

A practical implementation method of squeeze-film aeroelastic disk vibration damping and its practical design performance are presented to provide a solution method to meet the tight TMR(Track Mis-Registration) design budget of high-TPI HDDs. Most previous research results are mainly based on the component-level study in the 'open-cover state' which is far from the realistic operation HDD condition. In this study, the squeeze-film disk damping effect is widely investigated under the realistic drive-level condition of 'enclosed-cover state.' It is found that the proper aeroelastic gap(s) between disk(s) and adjacent surface(s) to give significant vibration reduction in the enclosed HDD operating conditions can be achieved not only by classical well-known squeeze-film damping gaps such as very small 0.0x-millimeter level gaps which are not practically implementable in mass-production HDDs, but also by a few 0.x millimeter which is possible for designing realistic HDD design. The various experimental results including drive-level PES are also presented to prove feasibility of the optimal disk damper design for 93kTPI HDDs.

• 한국주거학회논문집
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• 제23권2호
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• pp.79-87
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• 2012

The purpose of this study was to offer improvements, by deriving practical problems and suggesting ways to improve more realistic solutions in the multi-family housing management industry. This study is conducted in two ways. First, it was performed by reviewing related previous studies and clarifying major issues in the multi-family housing management. Second, it was performed by a questionnaire survey method, focused on the worker's opinions for that matters. The respondents work in an apartment in Seoul and the metropolitan area. A questionnaire distributed via e-mail, and then were collected. And questionnaire did not respond were excluded from the analysis. Finding were as follows -; first, it was possible to clarify four types regarding major issues in the multi-family housing management such as 'management system', 'housing management market conditions', 'management consciousness of resident', 'management performances'. Second, it was found that the competition was fierce in the same kind. And it was quite a high turnover rate of workers because of poor working conditions. Third, the most hard part was that the employee welfare was not good at work.

• 산업기술연구
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• 제26권A호
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• pp.55-61
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• 2006

Motorized retractors enhance the safety of passengers by removing the slack of webbing and by holding upright driving position. Reliability of a driving mechanism that includes one-way clutch between the driving motor and webbing is directly linked to the safety of passenger. In this research, conditions for locking one-way clutch, and also conditions for sustaining locking are theoretically investigated. The operation of a motorized retractor under realistic conditions is simulated in order to validate the proposed retractor design.

• 한국수자원학회논문집
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• 제57권4호
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• pp.249-261
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• 2024

최근 기후변화로 인해 극한홍수가 증가하여 댐 운영에 큰 어려움으로 작용하고 있다. 그간 댐 설계 시 제시되는 홍수조절방식은 하류 상황에 대한 고려 없이 계획홍수량이라는 특정 홍수상황을 가정하여 수립된 것으로, 실제 상황에는 기상예보를 기반으로 저수지 모의운영을 통해 홍수조절을 실시한다. 하지만 기상예보의 불확실성과 댐 관리자마다 달라지는 의사결정 등 한계가 존재한다. 따라서 본 연구에서는 섬진강댐에 대해 댐 유입량을 기준으로 댐 운영 제약사항을 고려한 단계적 방류량 증량을 실시하는 홍수조절방식을 제시하고, 계획홍수량 및 역대 최대홍수사상을 적용한 저수지 모의운영을 통해 효과를 평가하였다. 본 연구에서 제시한 홍수조절방식은 다양한 댐 운영자가 현실적 댐 운영 여건을 반영하여 일관성 있는 홍수조절 의사결정에 활용 가능할 것으로 판단된다.