• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.04a
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• pp.223-231
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• 1997

내열성복합재료와 Steel 구조물 사이의 좁고 긴 원통형 공간을 내열성 폴리우레탄 재료로 충전하는 연구를 수행하였다. 충전재료를 결정하기 위하여 3종의 폴리우레탄과 에폭시수지를 선정, 시험하여 내열성, 흐름성, 접착성, 경도측정 등을 통하여 최종 결정하였으며 선정된 폴리우레탄을 충전하기 위하여 Resin Transfer Molding(RTM) 방법을 사용하였다. 충전 공정의 적용여부를 판단하기 위하여 아크릴을 이용한 RTM치구를 설계, 제작하여 시험하였다. 충전된 조립체는 비파괴 검사를 통하여 접착, 기공 등을 검사하였으며 지상연소시험을 통하여 내열성능을 평가하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.406-407
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• 2009

The thermal protection techniques for ramjet combustor are key technology, which block the heat from hot combustion gas, and maintain the structure temperature safely. Film cooling method is one of them. This research proposes the optimal thermal design method through performing the study of thermal protection design for ramjet combustor.

• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.147-152
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• 2002

In the preceding tests of Sub.(Ⅰ) engines, it was observed that the heat resistant capability of the engines was not enough, and the design of Sub.(Ⅰ) engines was modified to satisfy the mission requirement. Sub.(Ⅰ) Mod. engines have three major design parameters - the arrangement of main injectors, the impinging angle of main injectors and thermal barrier coating. More than 20 experiments were carried out to evaluate engine performance and heat resistance capability with respect to design parameters. Analysing the result of Sub.(Ⅰ) and Sub.(Ⅰ) Mod. engine tests, it is found that the decreased impinging angle, adopting the H-type arrangement(rather than radial type arrangement), and adopting the thermal barrier coating can increase heat resistance capacity substantially. The result show that the performance variation by design change is below 5 percents and the radial type arrangement of injectors has higher performance than H-type. However, the performance of 15°impinging angle engine is higher than that of 20°impinging angle engine, which is inconsistent to our expectation. High frequency instabilities may cause such phenomenon, which will be verified by a series of tests.

• Journal of Korea Foundry Society
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• v.42 no.1
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• pp.3-11
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• 2022

In this study, the parameters on the shrinkage defect of HR3C alloy was secured through computer simulation research, and the ingot mold with greater than 85% of sound area was designed and manufactured. Moreover, the optimized coagulation was proposed at design stage through computer simulation and test was performed upon ingot manufactured. After the test, the defect pattern was analyzed through cutting and non-destructive inspection to verify the parameter and ingot mold design. Based on the verification results, shrinkage defect parameters such as Niyama, Feed Efficiency, and Hot Tear Intensity of HR3C Alloys were obtained. In addition, through the secured parameters, a plan for designing ingot mold with a Non-defect area of 85% or more was secured.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.1
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• pp.47-53
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• 2017

A boundary layer integral combined with a 1-D isentropic core flow model has been successfully used to determine heat transfer rate on the surface of a supersonic nozzle. However its accuracy is affected by the core flow condition which is used as a boundary condition for the integral calculation. Because flow behavior near a nozzle throat deviates from 1-D isentropic condition due to 2-D flow turning and interaction between core flow and boundary layer, accuracy of heat transfer calculation decreases at a nozzle throat. Therefore, CFD is adopted to deduce improved core flow condition and increase accuracy of boundary layer integral at nozzle throat in this research. Euler model and SST $k-{\omega}$ model is solved by CFD code and used as a boundary condition for boundary layer integral. Developed code is tested in the supersonic nozzle from the previous research and improvement in accuracy is observed, especially at nozzle throat and diverging section of the nozzle. Error between experimental result and calculation result reduced by 16% when a calculation is made based on the SST $k-{\omega}$ model. Method developed in this research is expected to be used in thermal design of the rocket nozzle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.257-260
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• 2010

The purpose of this paper is to introduce a method to predict the case thermal insulation charred and erosion thickness as a function of the exposure time to combustion gases and in solid rocket motors. The sizing of the insulator requires a good estimation of the thermal and mechanical loads at the wall. The method is particularly suitable for internal insulation areas subjected to high radiative, convective heat fluxes and $Al_2O_3$ slag pool. The mathematical approach and lab-scale experiment were intentionally simplified in order to obtain some simple and rapid relationships particularly useful for trade-off studies and thermal insulation preliminary design. The method was utilized to compute the charred and erosion thicknesses of the insulation on the aft chamber domes. A comparison between theoretical and experimental insulator char thicknesses of the motor insulation is reported, indicating the applicability of the predictive method employed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.6
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• pp.83-91
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• 2005

This paper describes the structural strength test technique and the results for cylindrical supersonic vehicle subjected to both aerodynamic load and thermal load. The special positioning system using spring links was designed to float, support and restrain the test airframe during the test and the down-time. The hydraulic system and the electric heating system were utilized to apply the aerodynamic load and the thermal load to the test airframe together. Particularly, several hundreds of infrared quartz lamps were used for the heating system, and the thermal test conditions were successfully simulated. The test results showed that this kind of high temperature test is adequate to verify the structure integrity and produce useful engineering data which is necessary for the possible structural modification under thermal environments.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.395-400
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• 2002

지역농가, 농협 단위로 그 지역에서 생산되는 특산물을 직접 살균 가공할 수 있는 연속살균공정과 장치를 설계할 수 있는 프로그램을 웹프로그래밍 언어의 일종인 JSP와 자바를 이용하여 개발하였다. 식품의 산성도 및 물리적 특성과 미생물의 내열특성 등 공정을 설계하는 데 필요한 전문적인 정보를 데이터베이스로 구축하여 사용자가 식품의 특성에 대해 자세하게 모르더라도 쉽게 식품의 살균공정을 설계할 수 있었다. 연속살균장치를 구성하고 있는 부분은 크게 열교환기와 가열유지관, 펌프이며, 이에 대한 설계를 장치 설계 프로그램에서 하였다. 열교환기, 가열유지관등의 설계는 장치의 생산량 및 가격등을 결정하는 주요 요소이며, 살균장치의 성능을 결정짓는 주요한 인자가 된다. 연속살균공정을 설계하는 데 필요한 인자는 식품의 pH특성, 식품의 종류이며, 입력된 값을 이용하여 데이터베이스 내에서 살균할 미생물의 종류와 미생물의 내열특성을 찾아 살균공정을 계산하게 된다. 프로그램을 통해 살균가능한 온도와 시간을 출력한다. 연속살균장치 설계 프로그램의 입력인자는 식품의 살균온도, 식품의 생산량, 열교환기에 사용할 열매체의 종류이며, 프로그램 내에서 열교환기의 전열계수, 식품을 살균온도가지 가열하는 데 걸리는 시간등이 계산되며, 결과값으로 열교환기의 특성 및 파이프의 구경과 길이, 펌프의 용량, 단열관의 구경과 길이가 출력된다. 살균 장치 중 열교환기의 설계에 사용되는 스테인레스 파이프를 국내에서 사용되는 규격별로 데이터베이스화하였으며, 파이프 제작업체 48개 업체, 펌프 제작업체 54개(국내 15개 업체, 미국 39개 업체), 열교환기 제작업체 13개업체(국내 13개 업체)에 대해서 데이터베이스를 구축하여 프로그램을 사용해 설계된 장치를 사용자가 쉽게 제작할 수 있도록 하였다. 공정설계프로그램을 통해 설계된 공정은 데이터베이스에 저장이 되며 장치설계프로그램에서 쉽게 이전에 설계했던 공정을 이용할 수 있도록 하여 공정 설계와 장치설계를 연계하도록 하였다.

• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.164-170
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• 2003

KSR-III engine with film-cooled baffle was tested. The purpose of this test is to verify the effect of ablative baffle on avoiding combustion instability which occurred in the acoustic cavity case. The engine had expansion ratio of 5.04 and the test condition was design condition(oxidizer mass flow rate 42.04, and fuel 17.95 kg/s). In the test, combustion instability did not occur. So, the effect of film-cooled baffle on avoiding combustion instability was verified.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1122-1126
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• 2017

KSLV-II ullage motor is a type of the separation motor of Korea Space Launch Vehicle. Simultaneously operates with the retro Motor to perform the stage separation. The internal ballistics design, application of propellant composition, and the design of the combustion chamber and the canted nozzle were performed in accordance with the target performance of the ullage motor. Ti-6Al-4V alloy was applied to the combustion as material of chamber and nozzle. The heat resistant material of the nozzle was selected to ensure the heat resistance of the propellant containing a large amount of aluminum. And the combustion performance of the ullage motor satisfying the KSLV-II requirements was secured by performing the ground combustion test.