Development of a University-Based Simplified H₂O₂/PE Hybrid Sounding Rocket at KAIST

Jeongmoo Huh,Byeonguk Ahn,Youngil Kim,Hyunki Song,Hosung Yoon,Sejin Kwon 한국항공우주학회 2017 International Journal of Aeronautical and Space Sc Vol.18 No.3

This paper reports development process of a university-based sounding rocket using simplified hybrid rocket propulsion system for low-altitude flight application. A hybrid propulsion system was tried to be designed with as few components as possible for more economical, simpler and safer propulsion system, which is essential for the small scale sounding rocket operation as a CanSat carrier. Using blow-down feeding system and catalytic ignition as combustion starter, 250 N class hybrid rocket system was composed of three components: a composite tank, valves, and a thruster. With a composite tank filled with both hydrogen peroxide(H₂O₂) as an oxidizer and nitrogen gas(N₂) as a pressurant, the feeding pressure was operated in blowdown mode during thruster operation. The MnO₂/Al₂O₃ catalyst was fabricated for propellant decomposition, and ground test of propulsion system showed the almost theoretical temperature of decomposed H₂O₂ at the catalyst reactor, indicating sufficient catalyst efficiency for propellant decomposition. Auto-ignition of the high density polyethylene(HDPE) fuel grain successfully occurred by the decomposed H₂O₂ product without additional installation of any ignition devices. Performance test result was well matched with numerical internal ballistics conducted prior to the experimental propulsion system ground test. A sounding rocket using the developed hybrid rocket was designed, fabricated, flight simulated and launch tested. Six degree-of-freedom trajectory estimation code was developed and the comparison result between expected and experimental trajectory validated the accuracy of the developed trajectory estimation code. The fabricated sounding rocket was successfully launched showing the effectiveness of the simplified hybrid rocket propulsion system.

집단미술치료 프로그램이 지역아동센터 이용 아동의 자아존중감에 미치는 영향

허정무(JeongMoo Hurh) 인문사회과학기술융합학회 2018 예술인문사회융합멀티미디어논문지 Vol.8 No.5

아동은 미술활동을 통해서 자신과 주변의 여러 가지 사물 및 타인과의 관계를 이해하고 자신의 생각을 표현하며 타인을 수용할 수 있다. 미술치료는 자신과 소통하고 내면을 자연스럽게 표현할 수 있는 정서적 지원방법으로서 그 중요성을 인정받고 있다. 미술치료를 통해 아동은 공격성, 불안, 억제된 감정 등을 분출함으로써 자신을 인식하고, 환경과 소통하는 통로를 열 수 있으며, 갈등을 조정하며, 자기표현 및 승화작용을 통해서 자아성장을 촉진할 수 있다. 이 연구에서는 지역아동센터 이용 아동들에게 집단미술치료 프로그램을 적용한 다음, 집단미술치료 프로그램이 지역아동센터 이용 아동의 자아존중감에 미치는 영향이 어떠한가를 알아보고자 하였다. 지역아동센터를 이용하고 있는 초등학교에 재학 중인 아동 20명을 대상으로 10명씩 실험집단과 통제집단에 배정하였다. 실험집단에 대해서는 집단미술치료 프로그램을 적용하였고 통제집단에 대해서는 지역아동센터의 자체프로그램을 적용하였다. 집단미술치료 프로그램에 따른 두 집단의 자아존중감의 변화를 비교하기 위해서는, 사후검사에 대해 사전검사 점수에 대한 효과를 제거하고 집단미술치료 프로그램에 따른 순수 효과를 분리 검출할 수 있도록 사전검사 점수를 공변량으로 하는 공변량분석을 적용하였다. 집단미술치료 프로그램을 적용한 결과 사전검사에 비해 사후검사의 자아존중감이 향상되는 효과가 나타났다. 이러한 집단 간의 차이는 집단미술치료 프로그램을 활용한 교육프로그램이 지역아동센터이용 아동의 자아존중감 향상에 긍정적인 영향을 주어 실험집단과 통제집단 간 사후검사 점수에 차이가 있는 것으로 확인되었다. Through art activities, a child can understand his or her various objects and relationships with others, express his/her thoughts, and accept others. Art therapy is recognized as important as an emotional support method to communicate with oneself and express inner feelings naturally. Through art therapy, the child can open a channel to communicate with the environment by recognizing himself/herself by spouting aggression, anxiety, and suppressed emotions, and can promote self-growth through coordination of conflicts, self-expression and sublimation. The purpose of this study was to investigate the effects of group art therapy programs on the children s self-esteem of community children centers. Twenty children were enrolled in the experimental group and the control group in the elementary school using the community children center. For the experiment group, the group art therapy program was applied. For the control group, the community children center program was applied. In order to compare the changes of self-esteem of the two groups according to the group art therapy program, the effect of the pre test score on the post test was removed and the pre test score was divided into Analysis of Covariance(ANCOVA). As a result of applying group art therapy program, self - esteem of post test was improved compared to pre-test. The difference between these groups was found to be the difference between post-test scores between the experimental group and the control group because the educational program using the group art therapy program positively affected the self-esteem improvement of the children using the community children center.

혼합모드 단일과대하중에 의한 하중상호작용이 피로균열 전파거동에 미치는 영향

이정무(Jeongmoo Lee),송삼흥(Samhong Song) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

In this study, when variable-amplitude load with various applying mode acts on the pre-crack tip, we examined how fatigue cracks behave. Hence aspects of the deformation caused by changing the applying mode of single overload and propagation behavior of fatigue crack were experimentally examined: What kinds of the deformation would be formed at pre-plastic tone could be evaluated? As applying mode of single of ·overloading changes, the deformation caused by tensile and shear loading variously showed in each applying mode. The different aspects of deformation make influence on propagation behavior between aspects of cracks under constant-amplitude fatigue loading after overloading with various modes. We tried to examine the relationship between aspects of deformation and fatigue behavior by comparing tire observed deformation at crack and crack propagation behavior obtained from fatigue tests.

변동모드와 변동진폭의 하중조합에 따른 피로거동의 특성

이정무(Jeongmoo Lee),송삼홍(Samhong Song),서기정(Kijeong Seo) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_2

In this study to execute the fatigue tests under combination load of variable-amplitude and variable-mode, loading mode was changed in each stage of single overload model. The shape and size of residual plastic deformation field which was formed by mixed-mode overloading were measured by using the C-scan method in this test. As applying mode of single overloading changes, the deformation caused by tensile and shear loading variously showed in each applying mode. The different aspects of deformation make influence on propagation behavior of cracks under constant-amplitude fatigue loading after overloading with various modes. Hence the propagation behavior in variable-mode and variable-amplitude load model was examined by considering the effects of load interaction for propagation behavior of fatigue cracks.

모드조합으로 구성된 단일과대하중모델의 지연거동에 대한 평가

이정무(Jeongmoo Lee),서기정(Kijeong Seo) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

In this study the propagation behavior of fatigue crack was evaluated with mode combination and change under single overloading and constant-amplitude loading conditions. This experimental model is single overload model consisted of mode combination. Modified compact tension shear specimen and mode-adjustable loading device were used in order to mode combination and change. We investigated change of fatigue life and characteristics of crack propagation behavior due to mode combination. The retardation area induced by mode combination was estimated by introducing mixed-mode overload plastic zone. We simplified types of retardation curves and established the assessment method for various retardation behaviors with mode combination by introducing retardation coefficient.

응력비 변화에 따른 FEM Carrier용 PP-LFT 소재의 피로 거동

이정무(Jeongmoo Lee),문종신(Jongsin Moon),오수석(Suseok Oh),백치경(Chikyoung Bae) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2007 No.11

EWF 방법을 이용한 CVJ Boots용 소재의 파괴거동 고찰

이정무(Jeongmoo Lee),최병호(Byoungho Choi),문종신(Jongsin Moon),이언석(Eonseok Lee) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

DELLA Proteins and Their Interacting RING Finger Proteins Repress Gibberellin Responses by Binding to the Promoters of a Subset of Gibberellin-Responsive Genes in <i>Arabidopsis</i>

Park, Jeongmoo,Nguyen, Khoa Thi,Park, Eunae,Jeon, Jong-Seong,Choi, Giltsu American Society of Plant Biologists 2013 The Plant cell Vol.25 No.3

<P>This work shows that DELLA proteins physically interact with a member of the BOTRYTIS SUSCEPTIBLE1 INTERACTOR (BOI) protein family and bind to GA-regulated gene promoters to repress GA-induced responses like seed germination, juvenile-to-adult phase transition, and flowering.</P>

Development of a University-Based Simplified H₂O₂/PE Hybrid Sounding Rocket at KAIST

Huh, Jeongmoo,Ahn, Byeonguk,Kim, Youngil,Song, Hyunki,Yoon, Hosung,Kwon, Sejin The Korean Society for Aeronautical and Space Scie 2017 International Journal of Aeronautical and Space Sc Vol.18 No.3

This paper reports development process of a university-based sounding rocket using simplified hybrid rocket propulsion system for low-altitude flight application. A hybrid propulsion system was tried to be designed with as few components as possible for more economical, simpler and safer propulsion system, which is essential for the small scale sounding rocket operation as a CanSat carrier. Using blow-down feeding system and catalytic ignition as combustion starter, 250 N class hybrid rocket system was composed of three components: a composite tank, valves, and a thruster. With a composite tank filled with both hydrogen peroxide($H_2O_2$) as an oxidizer and nitrogen gas($N_2$) as a pressurant, the feeding pressure was operated in blowdown mode during thruster operation. The $MnO_2/Al_2O_3$ catalyst was fabricated for propellant decomposition, and ground test of propulsion system showed the almost theoretical temperature of decomposed $H_2O_2$ at the catalyst reactor, indicating sufficient catalyst efficiency for propellant decomposition. Auto-ignition of the high density polyethylene(HDPE) fuel grain successfully occurred by the decomposed $H_2O_2$ product without additional installation of any ignition devices. Performance test result was well matched with numerical internal ballistics conducted prior to the experimental propulsion system ground test. A sounding rocket using the developed hybrid rocket was designed, fabricated, flight simulated and launch tested. Six degree-of-freedom trajectory estimation code was developed and the comparison result between expected and experimental trajectory validated the accuracy of the developed trajectory estimation code. The fabricated sounding rocket was successfully launched showing the effectiveness of the simplified hybrid rocket propulsion system.

소형 사운딩 로켓 적용을 위한 H2O2/PE 하이브리드 로켓 시스템

허정무(Jeongmoo Huh),정상우(Sangwoo Jung),김영일(Youngil Kim),안병욱(Byeonguk Ahn),최석민(Sukmin Choi),이재완(Jaewan Lee),송현기(Hyunki Song),김종학(Jonghak Kim),윤호성(Hosung Yoon),권세진(Sejin Kwon) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.11

250 N 급 과산화수소/폴리에틸렌 하이브리드 로켓을 추진시스템으로 이용하는 캔 위성 발사를 위한 소형 과학로켓 설계가 진행되었다. 내탄도 계산을 통한 추진기관 성능예측, 추진기관 제작 및 지상성능 시험이 수행되었으며, 과학로켓 운용 고도 계산을 위한 궤적 시뮬레이션 코드가 작성되었고 공개 코드계산결과와 비교를 통하여 정확성이 검증되었다. 추진 기관의 지상 시험결과는 촉매점화방식으로 촉매반응기 외에 추가적인 점화시스템이 요구되지 않는 과산화수소/폴리에틸렌 하이브리드 로켓 시스템의 높은 점화 신뢰성과 간소화된 시스템 구성이 가능함을 보여주었으며, 설계된 하이브리드 소형 과학로켓은 궤적 시뮬레이션 결과 최대 고도 700m의 운용 가능성을 보여주었다. Small scale sounding rocket as CanSat carrier was conceptually designed using 250 N class H2O2/PE hybrid rocket. Propulsion system was manufactured and ground tested. Internal ballistics was calculated for performance estimation of the propulsion system. The performance test of the propulsion system was successfully conducted showing ignition reliability and system simplicity, using catalyst ignition hybrid rocket with blow-down feeding system. For flight simulation of the designed sounding rocket, trajectory code was developed and validated. The trajectory simulation was conducted with expected altitude of 700 m for the designed sounding rocket.