• 한국항공우주학회지
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• 제41권5호
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• pp.383-390
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• 2013

유도탄의 사출성능 중 탄에 충격으로 작용하는 최대가속도의 감소는 유도탄의 비정상작동 방지와 내부 부품들의 크기 및 비용 감소 측면에서 매우 중요하다. 본 연구에서는 사출용 가스발생기의 작동에 의해 탄에 가해지는 최대가속도가 사출초기에 발생됨을 착안하여 사출초기에 영향을 미치는 설계인자를 조사하였다. 가스발생기 설계인자로 점화기 및 노즐마개를 선정하고, 설계인자 변경을 통해 가스발생기에 의해 발생되는 최대가속도를 실험적으로 조사하였다. 최종적으로 최대가속도 감소효과를 정량적으로 비교하기 위해 가스발생기 지상연소시험을 실시하였다. 그 결과 설계인자의 최적값들이 적용된 개선모델의 경우 기준모델에 비해 최대가속도를 약 68% 줄일 수 있음을 확인하였다.

• Journal of Trauma and Injury
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• 제21권2호
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• pp.100-107
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• 2008

Purpose: A traumatic lung cyst (TLC) is a rare complication and is usually detected with a pulmonary contusion. This study attempted to identify the prognostic factors and the clinical characteristics for pulmonary contusion with TLCs. Methods: We retrospectively reviewed the medical records and chest CT findings of 71 TLC patients who visited our hospital from January 2006 to December 2007. Patients were assessed for any clinical characteristics. We evaluated significant differences between the survival and the death groups for patients with a traumatic lung cyst. Results: The male-to-female ratio of patients with TLCs was 54:17, and the mean age of the patients was $37.70{\pm}19.78years$ with 36.6% of the patients being under 30 years fo age. The cause of blunt thoracic trauma was mainly pedestrian traffic accidents (26.8%) and falls (25.4%). Associated conditions included pulmonary contusion in 68 patients (95.7%), hemopneumothorax in 63 patients (88.7%), and rib fracture in 52 patitents (73.2%). There was no consistent relationship between the number of TLCs and the pulmonary contusion score. The overall mortality rate of TLC patients was 26.8%. Death correlated with a need for ventilatory assistance, mean arterial pressure, worst mean arterial pressure in 24 hours, initial pH and base excess, worst pH and base excess in 24 hours, refractory shock, initial GCS score, and pulmonary contusion score. Conclusion: The presence of the aforementioned predictors indicate serious injury, which is the main determinant of the outcome for thoracic injuries with TLCs.

• 한국추진공학회지
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• 제25권2호
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• pp.110-118
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• 2021

액체로켓엔진의 구성품인 연소기 산화제 개폐밸브는 연소기에 공급되는 산화제를 제어한다. 밸브가 닫힐 때 산화제는 연소기 대신 재순환 유로로 공급되며, 이때 발생한 수격현상에 의해 설계 기준보다 큰 압력이 발생할 수 있다. 본 연구에서는 액체질소를 운용 유체로 사용하여 재순환 유로의 초기 조건에 따른 수격 시험을 수행하였으며, 그 결과 발생하는 압력파를 분석하였다. 초기 조건에 따라 재순환유로 내부 압력파의 경향이 달랐으며, 특히 재순환 유로 끝단에서는 응축에 의한 수격이 발생할 때 압력이 최대로 커질 수 있음을 확인하였다.

• Journal of Chest Surgery
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• 제41권3호
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• pp.329-334
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• 2008

배경: 경피적 순환 보조장치는 다른 수단으로는 소생이 불가능한 심인성 쇼크 환자에 있어서 매우 효과적인 생명유지 장치이다. 특히 심근경색 및 고위험군의 관상동맥중재술, 심장수술 후 심인성 쇼크 등 다양한 임상상황에서 사용되며, 사용이 손쉬운 장점을 가지고 있다. 저자들은 급성 심근경색으로 입원한 환자 중 심인성 쇼크가 발생하여 경피적 순환 보조장치를 사용한 환자들의 초기경험을 분석하였다. 대상 및 방법: 2005년 1월부터 2006년 12월까지 급성 심근경색에 의한 심인성 쇼크 환자 8명에게 경피적 순환 보조장치(CAPIOX emergent bypass system, $EBS^{(R)}$, Terumo Inc., Tokyo, Japan)를 적용하였다. Seldinger방법을 사용하여 대퇴정맥에 20Fr의 유입관을 우심방까지 거치하고, 대퇴동맥에 16Fr의 유출관을 거치하면서 동시에 자가 충진을 완료하였다. 혈류량을 $2.5{\sim}3.0L/min/m^2$으로 유지하였고, 헤파린을 정주하면서 ACT를 200초 이상으로 유지하였다 결과: 환자의 평균나이는 $61.1{\pm}14.2$세($39{\sim}77$세)였다. 관상동맥중재술(PCI) 시행 이전에 거치한 경우가 3예, 중재술 도중 발생하여 거치한 경우가 3예, 중재술 후가 1예, 관상동맥우회술 후가 1예였다. 평균 $EBS^{(R)}$가동시간은 $47.5{\sim}27.9$시간$(8{\sim}76$시간)이었으며, 이 중 $EBS^{(R)}$ 이탈이 가능하였던 경우가 5명(62.5%)으로 이들은 모두 퇴원이 가능하였다. $EBS^{(R)}$적용으로 인한 합병증은 모두 3예로 급성 신부전이 2예, 위장관 출혈이 1예 있었다. 사망한 3명의 환자 중 2명은 $EBS^{(R)}$ 적용 전 심정지가 와 있었던 경우였으며, 1명은 난치성 심실세동이 있었던 경우였다. 퇴원한 환자는 모두 생존하여 평균 $16.8{\pm}3.1$개월($12{\sim}20$개월)째 외래 추적관찰 중이다. 결론: 다른 방법으로 소생이 힘든 급성 심근경색으로 인한 심인성 쇼크 환자에게 $EBS^{(R)}$를 적용함으로써 환자의 생명을 구할 수 있었고, 일단 회복된 환자들은 별다른 후유증 없이 생존하였다. 향후 $EBS^{(R)}$의 적절한 적용시기와 적용방법에 대해서는 보다 많은 경험 및 임상연구가 필요할 것으로 생각된다.

• 항공우주기술
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• 제6권1호
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• pp.190-200
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• 2007

파이로젠 형 점화기를 KSLV-I 킥모터 시스템 요구 조건을 만족하도록 설계하였다. 비행모델 제작에 앞서 신뢰성을 확보하기 위해 구조시험, 환경시험, 연소시험을 수행하였다. 점화기 구성품들의 구조적 강도를 확인하기 위해 수압 시험을 수행하였다. 극심한 환경 조건에서 점화기가 정상적으로 작동하는 지를 확인하기 위해 충격 및 진동 시험을 고려하였다. 그리고 초기 조건의 변화에 따른 점화 특성을 이해하기 위해서 연소시험을 수행하였다. 최종적으로 지상 시험을 통해 킥모터 추진제를 점화시키기에 충분한 에너지를 공급할 수 있다는 것을 검증하였다.

• Journal of Biosystems Engineering
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• 제37권1호
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• pp.51-57
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• 2012

Purpose: The compression strength of corrugated fiberboard containers used to package agricultural products rapidly decreases owing to various environmental factors encountered during the distribution of unitized products. The main factors affecting compression strength are moisture absorption, long-term top load, and fatigue caused by shock and vibration during transport. This study characterized the durability of corrugated fiberboard containers for packaging fruits and vegetables under simulated transportation conditions. Methods: Compression tests were done after corrugated fiberboard containers containing fruit were vibrated by an electro-dynamic vibration test system using the power spectral density of routes typically traveled to transport fruits and vegetables in South Korea. Results: To predict loss of compression strength owing to vibration fatigue, a multiple nonlinear regression equation ($r^2=0.9217$, $RMSE=0.6347$) was developed using three independent variables of initial container compression strength, namely top stacked weight, loading weight, and vibration time. To test the applicability of our model, we compared our experimental results with those obtained during a road test in which peaches were transported in corrugated containers. Conclusions: The comparison revealed a highly significant ($p{\leq}0.05$) relationship between the experimental and road-test results.

• 한국군사과학기술학회지
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• 제10권4호
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• pp.12-19
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• 2007

In this study, nonlinear flow-induced vibration(flutter) analyses of a 2-DOF launch vehicle airfoil have been conducted in supersonic and hypersonic flow regimes. Advanced aeroelastic analysis system based on computational fluid dynamics and computational structural dynamics is successfully developed and applied to the present analyses. Nonlinear unsteady aerodynamic analyses considering strong shock wave motions are conducted using inviscid Euler equations. Aeroelastic governing equations for the 2-DOF airfoil system is solved by the coupled integration method with interactive CFD and CSD computation procedures. Typical wedge type airfoil shapes with initial angle-of-attacks are considered to investigate the nonlinear flutter characteristics in supersonic(15). Also, the comparison of detailed aeroelastic responses are practically presented as numerical results.

• 한국군사과학기술학회지
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• 제19권4호
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• pp.545-550
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• 2016

Demilitarization involves the disposal and recovery of obsolete explosives or ammunition. Cyclotol has been used as a military explosive along with RDX and HMX. A limited number of processes exist for safe disposal due to their sensitivity to thermal shock. Rotary kilns are widely used for thermal decomposition in many countries due to cost effectiveness and simplicity compared with supercritical oxidation. Phase change as well as condensed phase reactions(CPRs) and gas phase reactions(GPRs) with rates described by the Arrhenius equation of cyclotol has been considered in this work. Changes in gas fraction, reaction rate and mass of explosives were predicted at 490, 505 and 575 K. A maximum temperature of 2062 K has been predicted within the reactor at an initial temperature of 575 K due to GPRs. From this research, Thermal decomposition in the rotary kiln is plausible for demilitarization.

• 한국기계가공학회지
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• 제10권4호
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• pp.16-21
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• 2011

This paper described an analysis of dynamic mechanism for the industrial two-step folding automatic door using commercial software packages. Two modeling types of operating on the guide rail, the sliding one and the rolling, were adopted to investigate effects of impact force when the door ascends the guide rail. The magnitude of impact force was found very peaklike large over an initial duration of the door's moving up. The amount of damping coefficient for alleviating this shock was controlled to such a moderate degree that the operating conditions can be obtained for the purpose of design. Moreover the behavior of both dynamic stress and deformation were observed for acquirement of structural reliabilities of the combined guide rail and rolling mechanism. This research will be a very useful tool in the near future for the dynamic analysis of the multi-step folding automatic door.

• Journal of Trauma and Injury
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• 제24권1호
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• pp.52-55
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• 2011

The spleen is the most frequently injured organ following blunt abdominal trauma. However, delayed splenic rupture is rare. As the technical improvement of computed tomography has proceeded, the diagnosis of splenic injury has become easier than before. However, the diagnosis of delayed splenic rupture could be challenging if the trauma is minor and remote. We present a case of delayed splenic rupture in a patient with underlying liver cirrhosis. A 42-year-old male visited our emergency department with pain in the lower left chest following minor blunt trauma. Initial physical exam and abdominal sonography revealed only liver cirrhosis without traumatic injury. On the sixth day after trauma, he complained of abdominal pain and diarrhea after eating snacks. The patient was misdiagnosed as having acute gastroenteritis until he presented with symptoms of shock. Abdominal sonography and computed tomography revealed the splenic rupture. The patient underwent a splenectomy and then underwent a second operation due to postoperative bleeding 20 hours after the first operation. The patient was discharged uneventfully 30 days after trauma. In the present case, the thrombocytopenia and splenomegaly due to liver cirrhosis are suspected of being risk factors for the development of delayed splenic rupture. The physician should keep in mind the possibility of delayed splenic rupture following blunt abdominal or chest trauma.