• 제어로봇시스템학회논문지
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• 제8권7호
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• pp.613-623
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• 2002

Ascent trajectory optimization and explicit guidance problems for a satellite launch vehicle with yaw maneuver in a 3-dimension are considered. The trajectory optimization problem with boundary conditions is formulated as a nonlinear programming problem by parameterizing the inertial pitch and yaw attitude control variables, and is solved by using the SQP algorithm. The flight constraints such as gravity-turn and range safety conditions are imposed. An explicit inertial guidance algorithm in the exoatmospheric phase is also presented. The guidance algorithm provides steering command and time-to-go value directly using the current states of the vehicle and the desired orbit insertion conditions. The liquid propelled Delta 2910 launch vehicle is used as a numerical model.

• Journal of International Society for Simulation Surgery
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• 제3권2호
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• pp.80-83
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• 2016

A 37-year-old male was assaulted and complained of severe periorbital swelling. Physical examination revealed that there were limitation of eyeball movement on upper gaze, diplopia, and hypoesthesia on the infraorbital nerve innervating region. Three-dimensional (3D) computed tomography (CT) of facial bone exhibited the fracture of orbital floor accompanying the significant amount of orbital contents' herniation extending to the far posterior part. To recover the orbital volume and restore orbital floor without threatening the optic nerve, preoperative simplified simulation was applied. The posterior margin of the fractured orbit was delineated with simulation technique using cross-linkage between the coronal and sagittal sections based on the referential axial view of the CT scans. Dissection, reduction of orbital contents, and insertion of the absorbable mesh plate molded after the prefabricated template by the simulation technique was performed. Extensive orbital floor defect was successfully reconstructed and there were no serious complications. The purpose of this report is to emphasize the necessity of preoperative simulation in case of restoring the extensive orbital floor defect.

• International Journal of Aeronautical and Space Sciences
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• 제5권2호
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• pp.54-61
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• 2004

In this paper we carried out a design study for an unmanned Mars missionsuitable for Republic of Korea. The mission will use a KSLV series launch system,which is to place a one tonne payload into the LEO. We calculated the velocityincrements(AV) required for departure from Earth and insertion into the orbitaround Mars based on the mission opportunity data provided by NASA. Two typesof Mars modules - entry type and orbiter type - were considered in this studyWe calculated the mass of TPS(therma1 protection system) for the entry tvpe Marsmodule based on the heat transfer rate and heat load from the Mars atmosphere tothe surface of the TPS. The heat transfer rate and heat load were obtained throughan entry trajectory calculation. For the orbiter type Mars module, we calcuIated themass breakdown of the additional spacecraft which is to insert the Mars moduleinto the orbit around Mars. Other mass items were determined by proportioningfrom the existing Mars modules. This paper finally proposes the payload capacitiesfor each types of Mars modules.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
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• pp.179-182
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• 2011

비행축/자세제어용 단일추진제 추력기의 우주발사체 적용과 국내 설계개발 현황을 조사/분석하였다. 탑재체의 정확한 궤도투입을 위하여 정밀한 자세제어가 요구되는 발사체 최종 단은 대부분 비추력 성능이 우수하고 높은 신뢰도 확보가 가능한 단일추진제 하이드라진 추력기시스템을 장착한다.

• 한국항공우주학회지
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• 제43권11호
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• pp.984-997
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• 2015

달 착륙선과 탐사 로버로 구성된 창어 3호는 2013년 12월 1일 시창 위성 발사 센터에서 장정 3B 발사체를 이용하여 발사되었다. 약 5일의 직접 전이궤적을 지나 달 궤도에 진입한 창어 3호는 달의 공전궤도에서 약 8일간 머무르다가 달 표면에 성공적으로 착륙하였다. 창어 3호의 성공적인 착륙은 한국의 달 탐사선 개발이 예정된 상황에서 향후 필요한 서브시스템의 기술 등을 분석하고, 발사에서 달 착륙까지의 궤적 및 운영 시퀀스 등을 도출하는데 많은 도움이 된다. 따라서 해외 언론에서 공지된 발사 현황을 바탕으로 창어 3호의 형상 및 전반적인 임무내용을 분석하고 시뮬레이션을 수행하였다. 그 결과 경계조건을 이용하여 제어변수를 추정 및 수렴값을 도출하여 착륙선의 전반적인 궤적을 생성하였다. 또한 이를 기반으로 교신 현황 및 식 현상을 분석하여 교신 및 전력충전이 양호함을 확인하였으며, 속도증분(${\Delta}V$)을 이용하여 비추력에 따른 착륙선의 여유 질량을 도출하였다.

• Archives of Plastic Surgery
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• 제34권5호
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• pp.599-604
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• 2007

Purpose: Blowout fractures of the orbit are common sequelae to blunt facial trauma and now increasing in number due to automobile accidents, violence and industrial disasters. There are some reports of diagnosis and treatment of this fracture, but detailed data provided in overall aspects are very few. We analysed extensive data to provide guide line of blowout fracture patients care. Methods: We retrospectively studied 387 orbital blowout fracture patients who had been followed up at least 3-6 months. Their hospital records were reviewed according to causes, fracture site, operation methods, and follow up results, etc. Results: The ratio of males to females was 7 : 3 and fractures were most often seen in the 20-29 age group. 180(47%) patients had medial orbital wall fractures, 155(40%) patients had floor fractures and 52(13%) patients had a combination of orbital floor and medial wall fractures. The highest associated bone fracture was the nasal bone(37%). The open reduction was done in the 324 patients(83.7%) and insertion materials were used in the 249 patients(77%). Total 45 patients(14%) complained of residual diplopia and 26 patients(8%) kept mild enophthalmos. 24 patients(7%) showed some restriction of extraocular muscle movements. Conclusion: We broadly surveyed the information of blow out fracture patients and believe that this study provides important prognostic information that can be of benefit to both patient and surgeon during preoperative counseling and postoperative analysis of orbital blowout fractures.

• Archives of Plastic Surgery
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• 제40권6호
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• pp.721-727
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• 2013

Background One of the main concerns in orbital blowout fracture repair is a narrow operation field, due mainly to the innate complex three dimensions of the orbit; however, a deep location and extensive area of the fracture and soft tissue edema can also cause concern. Swelling of the orbital contents progresses as the operation continues. Mannitol has been used empirically in glaucoma, cerebral hemorrhage, and orbital compartment syndrome for decompression. The authors adopted mannitol for the control of intraorbital edema and pressure in orbital blowout fracture repair. Methods This prospective study included 108 consecutive patients who were treated for a pure blowout fracture from January 2007 to October 2012. For group I, mannitol was administered during the operation. Under general anesthesia, all patients underwent surgery by open reduction and insertion of an absorbable mesh implant. The authors compared postoperative complications, the reoperation rate, operation time, and surgical field improvement between the two groups. Results In patients who received intraoperative administration of mannitol, the reoperation rate and operation time were decreased; however, the difference was not statistically significant. The total postoperative complication rates did not differ. Panel assessment for the intraoperative surgical field video recordings showed significantly improved vision in group I. Conclusions For six years, mannitol proved itself an effective, reliable, and safe adjunctive drug in the repair of orbital blowout fractures. With its rapid onset and short duration of action, mannitol could be one of the best methods for obtaining a wider surgical field in blowout fracture defects.

• Journal of Yeungnam Medical Science
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• 제13권1호
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• pp.22-31
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• 1996

본 교실에서는 1994년 11월부터 1996년 4월까지 수상 후 혹은 일차 교정 후 평균 3.2개월 경과한, 7명의 환자에서 제한된 접근방식으로 2차석 교정술을 시행하여 평균 4.5개월의 추적 조사한 후 만족할 만한 결과를 얻었으며 다음과 같은 결론을 내렸다. 1. 술전에 X-ray 검토, 사고 전의 사진, 충분한 대화 등을 토대로 가능한 정확한 절골선과 변형정도 등의 교정을 위한 계측이 필요하다. 2. 관골의 삼각골절 후 안면변형인 경우는 반드시 광범위 노출법보다는 제한적 방법으로 교정이 가능했다. 3. 절골된 관골은 내측 및 전상방으로 과교정해야 한다. 4. 절골 및 재배치시 저작근을 포함하여 주위 연부조직을 분리시키는 것이 중요하다. 5 안구함몰의 교정을 위해서 안와기저부 및 측부에 자가 골이식이나 고밀도 폴리에틸렌($Medpor^{(R)}$)의 삽입 후 결과의 차이는 발견할 수 없었다.

• 대한두개안면성형외과학회지
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• 제20권2호
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• pp.101-108
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• 2019

Background: To date, a variety of surgical approaches have been used to reconstruct the medial orbital wall fracture. Still however, there is still a controversy as to their applicability because of postoperative scars, injury of anatomical structures and limited visual fields. The purpose of this study was to introduce a useful additional medial subbrow approach for better reduction and securement more accurate implant pocket of medial orbital wall fracture with the subciliary technique. Methods: We had performed our technique for a total of 14 patients with medial orbital wall fracture at our medical institution between January 2016 and July 2017. All fractures were operated through subciliary technique combined with the additional medial subbrow approach. They underwent subciliary approach accompanied by medial wall dissection using a Louisville elevator through the slit incision of the medial subbrow procedure. This facilitated visualization of the medial wall fracture site and helped to ensure a more accurate pocket for implant insertion. Results: Postoperative outcomes showed sufficient coverage without displacement. Twelve cases of preoperative diplopia improved to two cases of postoperative diplopia. More than 2 mm enophthalmos was 14 cases preoperatively, improving to 0 case postoperatively. Without damage such as major vessels or extraocular muscles, enophthalmos was corrected and there was no restriction of eyeball motion. Conclusion: Our ancillary procedure was useful in dissecting the medial wall, and it was a safe method as to cause no significant complications in our clinical series. Also, there is an only nonvisible postoperative scar. Therefore, it is a recommendable surgical modality for medial orbital wall fracture.