• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.51-54
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• 2008

레이저는 다양한 빔 에너지의 분포 형상을 가질 수 있으며 크게 정형화된 분포 형상은 모드로 구분하여 모드에 따른 빔 에너지 분포 형상은 예측이 가능하다. 본 연구에서는 고에너지의 빔 분포 형상에 따른 steel의 가열 모델을 제시하고 빔 분포 형상에 따른 가열 패턴의 예측과 비교를 수행하였으며, 가열 패턴이 폭약의 점화에 미치는 영향에 대해 논의 하였다.

• 한국군사과학기술학회지
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• 제9권3호
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• pp.77-87
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• 2006

Micro- or nano-size particles are required to improve the combustion efficiency and stability in the case of solid explosives and propellants. The micro-structural properties of an energetic material strongly influence the combustion and explosion behavior. However, the traditional size reduction techniques, including milling, are not suitable for production of ultra-fine size particles. As an alternative to the traditional techniques, various re-crystallization processes based on supercritical fluids have recently been proposed. Supercritical fluids are fluids at temperatures and pressures above their critical point. In principle, they do not give problems of solvent contamination as they are completely released from the solute when the decompression occurs. Rapid Expansion Supercritical Solutions(RESS) and Supercritical Anti-Solvent Process(GAS/SAS) are representatives of a nano-size particle formation process of energetic materials using supercritical fluids. In this work, various fine particle formation processes using supercritical fluids are discussed and the results are presented.

• 한국입자에어로졸학회지
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• 제10권4호
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• pp.177-182
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• 2014

In this study, nickel-coated aluminum (Ni/Al) powders were synthesized for the utilization of energetic applications. Oxide materials present at the surface of Al powders of $45{\mu}m$ in averaged size were removed by using sodium hydroxide(NaOH) solution which is used for controlling pH. Nickel material is coated into the surface of oxide-removed Al powders by electroless-plating process. The microstructure of fabricated Ni/Al powders shows that nickel layers with a few hundreds nm were very homogeneously formed onto the surface of Al powders. The oxidation behavior of Ni/Al exihibit somewhat faster oxidation rate than that of pure Al with surface oxidation. Also, the higher exothermic reaction was observed from the Ni/Al powders. From the result of this, nickel coating is very promising method to obtain highly reactive and safe Al powders for energetic applications.

• Current Optics and Photonics
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• 제8권2호
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• pp.138-150
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• 2024

This study is essential for advancing our knowledge about the interaction between long-range high-power lasers and energetic materials, with a particular emphasis on understanding the response of a 155-mm shell under various surface irradiations, taking into account external factors such as atmospheric disturbances. The analysis addresses known limitations in understanding the use of non-realistic targets and the negligence of ambient conditions. The model employs the three-dimensional level-set method, computer-aided design (CAD)-based target design, and a message-passing interface (MPI) parallelization scheme that enables rapid calculations of the complex chemical reactions of the irradiated high explosives. Important outcomes from interaction modeling include the accurate prediction of the initiation time of ignition, transient pressure, and temperature responses with the location of the initial hot spot within the shell, and the relative magnitude of noise with and without the presence of physical ambient disturbances. The initiation time of combustion was increased by approximately a factor of two with atmospheric disturbance considered, while slower heating of the target resulted in an average temperature rise of approximately 650 K and average pressure increase of approximately 1 GPa compared to the no ambient disturbance condition. The results provide an understanding of the interaction between the high-power laser and energetic target at a long distance in an atmospheric condition.

• 한국추진공학회지
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• 제20권1호
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• pp.50-57
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• 2016

본 논문은 DNAM(Dinitroammeline)합성공정 개발을 위한 Lab scale 합성 과정을 소개하고 분석결과를 기록한 것으로 주요 내용은 다음과 같다 Melamine을 출발물질로 하여 니트로화와 산화 반응을 통해 DNAM을 합성하였다. 수율과 순도의 최적 조건을 찾기 위해 투입순서, 반응시간, 반응물 당량 등을 변경하여 실험을 수행하였다. DNAM 합성의 최적화된 조건은 3시간에서 3시간 30분 정도 반응시간이고, 니트로화 혼합물의 무게비는 1:1.4(아세트산 무수물:농질산)이며, 최종 수율은 60% 이상이다.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1400-1402
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• 2010

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1864-1866
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• 2013

• Journal of Electrochemical Science and Technology
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• 제7권3호
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• pp.190-198
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• 2016

Application of fuel cell to produce renewable energy for commercial purpose is limited by the high cost of Pt based electrode materials. Development of inexpensive, high energetic electrode is the need of the hour to produce pollution free energy using bio-fuel through a fuel cell. Ni-Cu and Ni-CeO₂-Cu electrode materials, electro synthesized by pulse current have been developed. The surface morphology of the electrode materials is controlled by different deposition parameters in order to produce a high current from the electro-oxidation of the fuel, the ethanol. The developed materials are electrochemically characterized by Cyclic Voltammetry (CV), Chronoamperometry (CA) and Potentiodynamic polarization tests. The results confirm that the high current is due to their enhanced catalytic properties viz. high exchange current density (i₀), low polarization resistance (R_p) and low impedance. It is worthwhile to mention here that the addition of CeO₂ to Ni-Cu has outperformed Pt as far as the high electro catalytic properties are concerned; the exchange current density is about eight times higher than the same on Pt surface. The morphology of the electrode surface examined by SEM and FESEM exhibits that the grains are narrow and sub spherical with 3D surface, containing vacancies in between the elongated grains. The fact has enhanced more surface area for electro oxidation of the fuel, giving rise to an increase in current. Presence of Ni, CeO₂, and Cu is confirmed by the XRD and EDXS. Fuel cell fabricated with Ni-CeO₂-Cu material electrode is expected to produce clean electrical energy at cheaper rates than conventional one, using bio fuel the derived from biomass.

• 한국추진공학회지
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• 제17권4호
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• pp.32-42
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• 2013

수치해석을 통하여 고에너지물질의 초음속 화염 전파에 대한 틈새(gap)의 효과를 연구하였다. 특성음향임피던스(characteristic acoustic impedance) 이론을 적용하여, 고폭약 및 고체추진제의 틈새(gap) 실험과 관계된 반사와 투과 현상들에 대한 이해를 추구하였다. 한편, 여러 개의 틈새(gap)가 위치하고 있는 화약의 한 끝에 초음속 화염이 발생되도록 하여, 여러 틈새(gap)에 전파되나가는 연속적인 화염에 대한 이해를 시도하였다. 이러한 고차원 다물질 해석을 통해, 충격하중 하에서의 고에너지 물질의 반응 특성이 물질 간격 동특성에 의하여 어떠한 영향을 받는지 이해할 수 있다.

• 폴리머
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• 제38권3호
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• pp.272-277
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• 2014

고온용 초음파 측정 시스템을 장착한 이축압출기를 이용하여 고에너지 물질 시뮬란트의 분산도를 실시간으로 모니터링하는 연구를 하였다. 결합제 수지 및 충전제로 ethylene vinyl acetate(EVA)와 Dechlorane plus 25를 각각 사용하여 고에너지 물질 시뮬란트 현탁계를 구성하였다. 충전 부피분율이 증가함에 따라 현탁계의 초음파 속도는 전혀 변화를 보이지 않았으나 초음파 감쇠는 선형적으로 감소하였는 바 고르게 분산된 현탁계를 대상으로 초음파 감쇠를 측정하면 충전함량을 추정할 수 있음을 확인하였다. 또한 60 v% 이상으로 충전된 고농축 현탁계에서는 반복 압출실험을 수행한 결과 초음파 감쇠의 편차가 감소하여 직선값에 접근하는 경향을 보이는 바 분산도의 증가하는 것을 알 수 있었다. 따라서 on-line 및 in-line으로 측정된 초음파 감쇠와 off-line으로 SEM 및 Image Analyzer 그리고 열중량분석을 병행함으로써 분산도 및 충전 함량을 평가할 수 있을 것으로 사료된다.