• Physical Therapy Korea
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• v.9 no.4
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• pp.13-35
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• 2002

Lesch-Nyhan 증후근(LNS)은 hypoxanthine guanine phosphoribosyle transferase(HGPRT) 효소를 암호화 하는 X 염색체가 불완전해서 일어나는 유전적인 추제외로계(또는 기저핵)의 드문 병변이다. 출생시 LNS 유아는 정상적인 운동발달이 관찰되어진다. LNS에게서 현저하게 진단적인 특징으로 보여지는 운동심리적 행동인 self-mutilating 행위는 4살 이후에나 나타난다. LNS 아이들은 오히려 초기에 Rett's 증후근, 뇌성마비, 자폐, 다운증후근과 유사한 운동행위를 보인다. 그래서 LNS 아이들은 앞에 기술한 신경학적 장애로 오진을 받을 수가 있다. 오진으로 인해 초기에 적절한 치료를 받지 못한다면 LNS는 결과적으로 합병증(신장부전)과 self-mutilating 행위로 인하여 치명적일 수가 있다. 그러므로, 이 연구의 목적은 LNS 평가 동안 더 나은 진단을 하도록 하기 위하여 LNS와 관련된 기능부전에 대한 지식을 임상가들에게 제공하고자 함이었다. 연구 대상자는 10살인 2명의 쌍둥이 남아이었으며 실험은 뻗기 과제 수행(reaching task)시 움직임 특성을 보기 위하여 운동형상학적과 비디오 분석을 사용하였다. 기술통계로 분석 결과 움직임 시간과 단위가 증가됨을 보였고 사지의 분절적 움직임이 협응되지 않음을 보였다. ballistic과 jerky 움직임 양상은 dysmetric과 비긴장성 운동 행위에서 우세하였다. LNS은 추체로계 운동 장애 (과근긴장도나 저긴장도) 와 추체외로계의 운동 장애(dystonia와 choreoathetosis)의 혼합된 형태를 보였다. 결론으로 이 연구는 운동발달 장애를 가진 아이들을 치료하고자 할 때 임상가들한테 LNS 아이들의 움직임 장애의 다른 진단적 특징을 알아야 한다는 것을 제시하고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.445-447
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• 2015

The situation in Northeast Asia is rapidly changed because of the territorial dispute between neighboring countries near the East China Sea, North Korean nuclear bomb tests, long-range ballistic missile launching tests frequently and deployment of Chinese Liaoning class aircraft carrier. Especially, unstable political situation of North Korea and Chinese A2/AD strategy by strengthening naval forces are the cause of replanning Asia-Pacific security strategy of Unites States. In this paper, it is surveyed and analyzed that changed Asia-Pacific security strategy of U.S. and rearrangement plan of U.S. Naval forces. And changed environmental situation influence on our security is analyzed.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.11
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• pp.361-368
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• 2015

In AAGFCS the effective range is regarded as a range for the bullet's speed exceeding the speed of sound to damage the stationary target. Hence the real engagement range might be extended over the effective range for the approaching target since bullet's relative speed to the target increases depending on the approaching speed. However previous TOF equations have good computation accuracy within the effective range only, and they can not be used above that range due to their bad accuracy. We propose an accurate TOF computation method which can be used both within and above the effective range in real time. Some simulation results are shown to demonstrate usefulness of our algorithm for the 30mm projectile.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.668-671
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• 2010

Comparative study on propellant modeling has been investigated using a non-dimensional method and an one-dimensional method. The propellant location in the chamber can not be described by the non-dimensional method. It is, however, possible for the one-dimensional method to describe. Therefore, the analysis of the interior ballistics according to the propellant arrangements has been performed by the one-dimensional method. The negative differential pressure in the chamber could be predicted and the necessity of the one-dimensional modeling for the analysis of the interior ballistics has been confirmed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.565-568
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• 2010

A pressure control law to regulate mass flow rate of gas generator is suggested. The governing equation is modeled by considering the burning rate of solid propellant and the conservation equation of gas generator. And then, a classical control law is applied after verifying the accuracy of dynamic model through comparing with ground test and internal ballistic results. The results show degradation of performance as shown in typical time varying system. To overcome this problem, an adaptive scheme is suggested and the performance is verified through numerical simulation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.664-667
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• 2010

Solid rocket propulsion systems are generally used for tactical missiles due to the structural and operational simplicity. Nevertheless, various kinds of design factors including outer diameter, length, weight, loading efficiency of propellant grain effects to thrust performance. Dual thrust is beneficial to range extension and terminal velocity increasement. But loading efficiency becomes low in case to obtain dual thrust performance by burning surface control. So, It is predicted to be reasonable to obtain dual thrust performance with high/low burning rate propellants. This study is on internal ballistic analysis and ground test to confirm dual thrust performance.

• International Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.29-33
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• 2015

The multidisciplinary design optimization (MDO) of a launch vehicle (LV) with a hybrid rocket engine (HRE) was carried out to investigate the ability of an HRE for a single-stage LV. The non-dominated sorting genetic algorithm-II (NSGA-II) was employed to solve two design problems. The design problems were formulated as two-objective cases involving maximization of the downrange distance over the target flight altitude and minimization of the gross weight, for two target altitudes: 50.0 km and 100.0 km. Each objective function was empirically estimated. Several non-dominated solutions were obtained using the NSGA-II for each design problem, and in each case, a trade-off was observed between the two objective functions. The results for the two design problem indicate that economical performance of the LV is limited with the HRE in terms of the maximum downrange distances achievable. The LV geometries determined from the non-dominated solutions were examined.

• International Commerce and Information Review
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• v.8 no.1
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• pp.371-398
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• 2006

Gold prices are rising around the world in all major currencies. This is a telltale sign of a Stage Two gold bull where gold decouples from the US dollar. In this study, We analysed a confluence of factors seem to be feeding gold's gains and the typical shape of a secular gold bull---gold bulls' three stages. Stages one, two, and three of a secular gold bull are defined by the major changes. Each stage, considered in turn, makes perfect sense when described in terms of global investor demand. Since Stage One is currency-devaluation driven, the young gold bull is most noticeable in terms of the dominant eroding currency. Now after three or four years of stage one, Stage Two arrives. Stage Two marks a momentous event when gold decouples from the local-currency devaluation. In the case of our gold bull today, Stage Two will be here when gold starts consistently rising faster than the dollar is able to fall. After five or so years of Stage Two gains, gold has a chance at going ballistic in stage three. Stage Three is only ignited if the general public around the world starts growing enamored with gold investing. In summary, the first stage being when insiders and professionals invest in the market. The second stage is when the general public and financial media recognizes that the bull market is real. The third stage is the mania stage when people feel that not only is the bull market real, but it is a must own situation. Through the study we found that gold is entering it now.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.687-692
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• 2004

For the prediction of sloshing in the propellant tank of rocket vehicle utilized in RVT (reusable rocket vehicle testing) conducted by ISAS/JAXA, the flow field in the propellant tank during the ballistic flight was experimentally reproduced with the sub-scale model of it. The lateral acceleration as large as about 0.8 G was provided with a mechanical exciter and the deformation of liquid surface in the vessel was visualized with a high-speed camera. The several con-figurations of damping devices were installed and tested in the vessel, which should keep the ullage gas away from the outlet port. It was consequently suggested that the combination of a baffle plate and a perforated cylinder could be effective against the gas suction before the re-ignition of the engine. The sloshing phenomena were also simulated with the CFD code, called CIP-LSM. The numerical results showed good agreement with the corresponding data obtained in the experiment.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1115-1121
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• 2017

In order to obtain high thrust at the beginning of the flight, the solid rocket motor with large initial burning surface area was designed and tested. From the static firing test, lower initial thrust was obtained compared with the expected thrust based on the internal ballistic prediction due to the negative erosive burning effect which reduced the burning rate estimated by APN Law. In addition, the radial mode combustion instability was observed with 8 fins grain configuration. This instability was removed after the odd number of fins were used.