• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.776-777
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• 2017

The grain burn-back analysis has been required for the calculation of the solid propellant performance. The conventional grain burn-back analysis uses the level set method, but problems in the moving surface analysis may occur. In this study, the face offsetting method has been used for analyzing the moving surface. As results, the face offsetting method has been proven to be useful method for the grain burn-back analysis.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.4
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• pp.81-91
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• 2019

The 3-dimensional grain burn-back analysis is performed using the face offsetting method for calculating the solid rocket motor performance. The grain burning configuration analysis is a moving surface problem that calculates the regression of the burning surface. In the previous study, various moving interface analysis methods were applied for the grain burn-back analysis, but the results were imperfect. In this study, a 3-dimensional grain burn-back analysis module is developed using the face offsetting method, which combines the advantages of the existing moving interface analysis methods to increase the accuracy and robustness. As a result, the face offsetting method is proved to be efficient for the grain burn-back analysis.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.3
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• pp.40-47
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• 2014

The grain burn-back analysis has been performed for the internal ballistics analysis code to be used for the optimal design of the space launch vehicles. The grain burn-back has been used to calculate the burning surface that is essential to the internal ballistics. The calculation of internal ballistics code used in the optimal design is repeated until satisfying the required performance through the change of the design parameter. Therefore, the burn-back method applied to the internal ballistics analysis should be easy to change the design parameter and calculation time should be short. In this study, a burn-back analysis code has been developed using the analysis method. Also, geometric parameters of the grain have been selected and organized. The developed code has been verified by comparison of results of a numerical method.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.2
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• pp.55-65
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• 2021

In this study, the design criteria is presented for Finocyl grain, which is easy to generate neutral thrust when designing solid rocket motors. For this purpose, an automated program using drafting method was developed for burn-back analysis and its accuracy was validated. Using this developed program, burn-back analysis was performed with various configuration parameters of Finocyl grain, and the tendency and sensitivity analysis on burning characteristics were performed. Based on this analysis, the design criteria were presented to generate the neutral burning surface area trace for a Finocyl grain.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.3
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• pp.22-31
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• 2022

Existing Finocyl grain designs assume configurations and repeat the process of configuration modification and confirmation of the requirements through burn-back analysis. Such a design increases the design fatigue of workers and has a problem of different design completeness depending on capabilities. Therefore, this study devised an optimal design method that applied genetic algorithms to the Burn-back automation analysis program to solve the problem of existing design. For stable search, variable-offset and non-drawable configuration control techniques were developed. The program performance was verified through the searching neutral and double thrust grains.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.2
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• pp.12-19
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• 2022

Propellant grains with embedded metal wires have been used for enhancement of burning rate while maintaining high loading density. For the performance design of a solid rocket motor using propellant grain with embedded metal wires, burn-back analysis is required according to number, location, arrangement angle of metal wires, and augmentation ratio of the propellant burning rate near a wire region. In this study, a numerical method to quickly calculate a burning surface area was developed in response to the design change of the propellant grain with embedded metal wires. The burning surface area derived from the developed method was compared with the results of a CAD program. Error rate decreased as the radial size of the grid decreased. Analysis for characteristics of burning surface area was performed according to the number and location of metal wires, the initial and final phases were shortened and the steady-state phase was increased when the number of metal wires increased. When arranging the metal wires at different radii, the burning surface area rapidly increased in the initial phase and sharply decreased in the final phase compared to the case where the metal wires were disposed in the same radius.

• Proceedings of the KSRS Conference
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• v.1
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• pp.336-339
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• 2006

In this paper, the preliminary transfer orbit analysis results for the COMS mission were presented. As the first step of transfer orbit analysis, the preliminary analyses of LAE burn strategy, geometrical visibility, and launch window were performed. For the analysis process, all launcher nominates were divided into three groups according to the declination of LAE thrust angle. So, the three launch cases were assigned as the representative launcher of each group, respectively. They are Ariane-5, Atlas summer and winter launch cases. And all analyses were performed at the representative launcher of each group. One nominal and three back-up plans were considered for the establishment of LAE burn strategy. And for geometrical visibility analysis, four TT&C ground stations were considered. Finally, the preliminary launch window analysis was performed about the duration of one year from the first day of September 2008. The analysis results show that the all launch cases comply with the transfer orbit operation requirements.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1556-1557
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• 2007

LCD BLU에 광원의 수명을 측정하고, 고장모드를 분석하기 위해서는 광원을 구성하고 있는 각각의 성분 중에서 광원 자체를 구성하고 있는 R/G/B 광원에 대한 Burn-in test 및 고장모드를 분석하였다. LCD BLU에 있어서 R/G/B LED광원의 역할은 BLU 자체의 수명과 성능에 가장 큰 영향을 미친다. 서로 각각 사용조건하에서의 수명과 성능의 차이에 따라서 BLU 자체의 수명이 결정된다. 이를 평가가기 위해 LED device에 대한 가속수명테스트를 위한 Burn-in test를 실시하였으며, 발생한 고장모드를 분석하였다. 분석결과 누설전류 증가로 인한 불량이 주로 발생하였다. 누설전류 증가를 평가하기 위해 Photo emission microscope(PHEMOS-1000, MoDooTEK Inc.)을 이용하여 저전류에서의 LED chip의 누설전류에 의한 발광을 관찰함으로 인해, LED chip의 신뢰성 및 평가 기준이 됨을 알 수 있다.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.36 no.6
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• pp.280-284
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• 2014

Purpose: This study evaluated woven silk textile for burn wound dressing materials in an animal model. Methods: Ten rats were used in this experiment. Full-thickness $2{\times}2cm$ burn wounds were created on the back of the rats under anesthesia. In the experimental group, the wounds were treated with three different dressing materials from woven silk textile. In the control group, natural healing without any dressing material was set as control. The wound surface area was measured at five days, seven days, and 14 days. Wound healing was evaluated by histologic analysis. Results: There were no statistically significant differences among groups at five days post injury. The mean defect size at seven days was largest in Group 3 ($462.87mm^2$), and smallest in Group 1 ($410.89mm^2$), not a significant difference (P=0.341). The mean defect size at 14 days was smallest at the Group 3 ($308.28mm^2$) and largest in the control group ($388.18mm^2$), not a significant difference (P=0.190). The denuded area was smaller in Group 1 ($84.57mm^2$) and Group 2 ($82.50mm^2$) compared with the control group ($195.93mm^2$), not statistically significant differences (P=0.066, 0.062). The difference between Group 3 and control was also not statistically significant (P=0.136). In histologic analysis, the experimental groups re-epithelialized more than control groups. No evidence was found of severe inflammation. Conclusion: The healing of burn wounds was faster with silk weave textile more than the control group. There was no atypical inflammation with silk dressing materials. In conclusion, silk dressing materials could be used to treat burn wounds.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.36 no.3
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• pp.111-115
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• 2014

Purpose: This study evaluated powdered burn wound dressing materials from wild silkworm fibroin in an animal model. Methods: Fifteen rats were used in this experiment. Full-thickness $2{\times}2cm$ burn wounds were created on the back of rats under anesthesia. In the two experimental groups, the wounds were treated with two different dressing materials made from silkworm fibroin. In the Control Group, natural healing without any dressing material was set as control. The wound surface area was measured at five days, seven days and 14 days. Wound healing was evaluated by histologic analysis. Results: By gross observation, there were no infections or severe inflammations through 14 days post-injury. The differences among groups were statistically significant at seven days and 14 days, postoperatively (P<0.037 and 0.001, respectively). By post hoc test, the defect size was significantly smaller in experimental Group 1 compared with the Control Group and experimental Group 2 at seven days postoperatively (P=0.022 and 0.029, respectively). The difference between Group 1 and Group 2 was statistically significant at 14 days postoperatively (P<0.001). Group 1 and control also differed significantly (P=0.002). Group 1 showed a smaller residual scar than the Control Group and Group 2 at 14 days post-injury. Histologic analysis showed more re-epithelization in Groups 1 and 2 than in the Control Groups. Conclusion: Burn wound healing was accelerated with silk fibroin spun by wild silkworm Antheraea pernyi. There was no atypical inflammation with silk dressing materials. In conclusion, silk dressing materials can be used for treatment of burn wound.