• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.467-468
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• 2011

• 대한치과기공학회지
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• 제8권1호
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• pp.51-55
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• 1986

The castability of base metal alloys for dental casting in influenced by burn-out temperature and recent percentage. Burn-out temperatures for casting are set at 200$^{\circ}F$ interval from 1000$^{\circ}F$ to 1800$^{\circ}F$. According to recast metal percent in new cast alloy metal alloys are tested. The results are as followings: 1. In the new alloy(100%), the castability is the most. 2. The burn-out temperature in 1600$\sim$1800$^{\circ}F$, castability of 100% new alloy was more four times than of 50% new alloy plus 50% recast alloy. The using of 50% new alloy and 50% recast alloy, therefore, was unlike in castability. 3. The burn-out temperature in 1600$^{\circ}F$, castability of 100% new alloy was more than four times in soaking 20 minutes, but there was no any difference at 18700$^{\circ}F$. 4. It is investigated that the optimal burn-out temperature is 1600$^{\circ}F$ for the C & B alloy.

• 대한화상학회지
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• 제22권2호
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• pp.66-70
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• 2019

Purpose: The necrotizing fasciitis is a terrifying infectious disease that can rapidly spreads to surrounding tissues when fascia is infected and it can cause sepsis to death if not properly diagnosed and treated. The purpose of this study is to investigate the characteristics, causes, and treatment methods of necrotizing fasciitis in Korea through reviewing patients admitted to our burn center. Methods: 21 patients with necrotizing fasciitis were selected for this study among those inpatients with electronic medical records (EMR) admitted to Hallym University Hangang Sacred Heart Medical Center from Jan 1, 2008 to June 30, 2019. The medical records and wound photos of those 21 selected subjects were reviewed. Results: There were 13 male and 8 female patients and mean age was 58.76 years old. 13 of 21 subjects were survived and 8 died (38% mortality rate). The surgical treatments performed were I&D, fasciotomy, debridement, allograft, burring, STSG, flap, and amputation. The most common causes were burns in 9 subjects (6 contact burns) and cellulitis occurred on skins in 5 subjects. And other various causes were observed as fournier's gangrene, stab wound, intramuscular injection, tumor and bleu toe syndrome (toe necrosis). The infected areas were 11 feet and legs, 7 hips, 3 abdomen and trunk in 21 subjects. Of the 8 deaths, 3 were infected in feet and legs, 2 were infected in hips, and 2 were infected in abdomen and trunk. As for underlying diseases, 12 patients with hypertension or diabetes were the highest and others such as cancer and stroke were found. Conclusion: The only method to increase the survival rate is to 'suspect' the disease as much as possible and perform early extensive excision. It is advisable to treat the disease by the burn center to properly provide adequate and optimal wound management, infection control, medical care and nutritional supports.

• 대한기계학회논문집
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• 제19권3호
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• pp.763-770
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• 1995

Gas flow characteristics within the cylinder is important factors in impoving lean combustion stability. This paper shows the effects of various flow fields generated by a swirl control valve(SCV) on combustion process in a 4-valve spark ignition engine. An impulse swirl/tumble meter was used to elucidation the steady-state flow characteristics, and a rotating grating type LDV was developed to measure the mean velocity and tunbulence intensity in relation to the crank angle. These methodologies were applied to clarify the correlation between gas flow characteristics and combustion stability at a lean air fuel ratio. An analysis of the correlation revealed the gas flow conditions required to optimize a lean-burn system.

• 대한화상학회지
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• 제24권2호
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• pp.46-49
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• 2021

An anatomically normal first web space is essential for optimal prehensile movements of the thumb and hand. A 28-year-old woman presented with severe scarring and contractures of the first web space of both hands, following a flame burn injury sustained 25 years prior to presentation. First web space contracture may occur secondary to severe injuries, burns (as observed in our patient), or congenital hand anomalies. A significant amount of additional skin is required to release a severe first web space contracture. Reconstruction of wide areas of contractures using only local flaps is challenging. Among other free flaps used in clinical practice, the thinned lateral arm free flap provides flexible vascularized tissue for reconstruction of the skin after severe first web space contracture release. Reconstruction using lateral arm free flaps facilitated thumb abduction and opposition (which were initially difficult) and improved hand function in our patient.

• 항공우주시스템공학회지
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• 제10권4호
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• pp.90-97
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• 2016

항공우주연구원은 천리안위성의 임무를 승계하기 위해 2018년과 2019년 발사를 목표로 정지궤도복합위성 2A와 2B를 개발하고 있다. 정지궤도복합위성은 아리안 V 발사체에 의하여 발사되어 전이궤도(Transfer Orbit)에 전입한 후 여러 번의 액체원지점엔진분사를 통하여 표류궤도에 진입한다. 액체원지점엔진의 분사시기, 분사시간, 각 분사간의 간격 등은 위성이 목표하는 표류궤도에 진입할 수 있도록 선정되고 적용된다. 정지궤도복합위성의 경우 표류궤도 진입을 위하여 4회의 액체원지점엔진 분사를 수행할 계획이다. 본 논문에서는 미리 정의된 제한조건을 고려하고 외부 교란력을 고려하여 정지궤도복합위성의 액체원지점엔진 분사계획을 수립하였다. 여기서는 단일계산(Single Shot) 방식과 반복계산에 의한 최적화 기법, 두 가지 접근을 고려하였다. 최적의 해를 얻기 위해 Focusleop이라고 하는 발사초기임무해석 도구를 적용하였다.

• 한국항공우주학회지
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• 제38권10호
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• pp.998-1011
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• 2010

본 연구에서는 미래 한국의 달탐사에 대비, 제한추력을 이용한 최적의 지구-달 천이궤적 설계를 수행하였다. 보다 실제적인 임무 시나리오 설계를 위해 달 천이 (Trans Lunar Injection, TLI) 기동에 사용되는 발사체 상단 킥모터의 추력 성능을 제한하였다. 이를 바탕으로 지구 출발부터 달 근접에 이르는 지구-달 천이비행궤적이 설계되었으며, 제한추력을 이용하여 설계된 비행 궤적의 최적화 결과와 순간추력을 이용하여 최적화된 결과가 비교 분석되었다. 만약 순간추력을 이용해 도출된 예비 임무 설계의 결과가 제한추력을 가정한 임무 설계를 위해 응용될 경우, 가정된 제한추력의 크기에 따라 다양한 범위의 기동량의 차이가 발생 할 수 있어 이에 따른 충분한 고려가 이루어져야 함을 확인하였다. 본 연구에서 제시된 제한추력을 이용한 달탐사 임무궤적 설계/해석 결과는 미래 한국의 달탐사를 대비하는데 있어 다양한 사전 지식을 제공할 것이며 장차 상세한 임무설계를 위한 알고리즘의 기반으로 사용될 수 있다.

• Archives of Plastic Surgery
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• 제45권2호
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• pp.118-127
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• 2018

Background A variety of island flaps can be based on the superficial temporal artery with variable tissue composition. They can be used for defect reconstruction, cavity resurfacing, facial hair restoration, or contracture release. Methods Seventy-two patients underwent facial reconstruction using a superficial temporal artery island flap from October 2010 to October 2014. The defects had various etiologies, including trauma, burns, tumors, exposed hardware, and congenital causes. We classified the patients by indication into 5 groups: cavity resurfacing, contracture release, facial hair restoration, skin coverage, and combined. The demographic data of the patients, defect characteristics, operative procedures, postoperative results, and complications were retrospectively documented. The follow-up period ranged from 24 to 54 months. Results A total of 24 females and 48 males were included in this study. The mean age of the patients was $33.7{\pm}15.6years$. The flaps were used for contracture release in 13 cases, cavity resurfacing in 10 cases, skin coverage in 17 cases, facial hair restoration in 19 cases, and combined defects in 13 cases. No major complications were reported. Conclusions Based on our experiences with the use of superficial temporal artery island flaps, we have developed a detailed approach for the optimal management of patients with composite facial defects. The aim of this article is to provide the reader with a systematic algorithm to use for such patients.

• Journal of Astronomy and Space Sciences
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• 제28권3호
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• pp.203-216
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• 2011

To prepare for a future Korean lunar orbiter mission, semi-optimal lunar capture orbits using finite thrust are designed and analyzed. Finite burn delta-V losses during lunar capture sequence are also analyzed by comparing those with values derived with impulsive thrusts in previous research. To design a hypothetical lunar capture sequence, two different intermediate capture orbits having orbital periods of about 12 hours and 3.5 hours are assumed, and final mission operation orbit around the Moon is assumed to be 100 km altitude with 90 degree of inclination. For the performance of the on-board thruster, three different performances (150 N with $I_{sp}$ of 200 seconds, 300 N with $I_{sp}$ of 250 seconds, 450 N with $I_{sp}$ of 300 seconds) are assumed, to provide a broad range of estimates of delta-V losses. As expected, it is found that the finite burn-arc sweeps almost symmetric orbital portions with respect to the perilune vector to minimize the delta-Vs required to achieve the final orbit. In addition, a difference of up to about 2% delta-V can occur during the lunar capture sequences with the use of assumed engine configurations, compared to scenarios with impulsive thrust. However, these delta-V losses will differ for every assumed lunar explorer's on-board thrust capability. Therefore, at the early stage of mission planning, careful consideration must be made while estimating mission budgets, particularly if the preliminary mission studies were assumed using impulsive thrust. The results provided in this paper are expected to lead to further progress in the design field of Korea's lunar orbiter mission, particularly the lunar capture sequences using finite thrust.

• 대한화상학회지
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• 제24권2호
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• pp.68-73
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• 2021

Purpose: A large defect by fourth-degree burns in the upper limb requires flap reconstruction. Since severe vascular damage and decrease in blood circulation after vascular anastomosis can occur in defects caused by fourth-degree burns. Because of the disadvantages, it is difficult to apply free flap surgery to fourth-degree burns. We reconstructed a upper extremity using the pedicled Latissimus Dorsi (LD) flap in two stages. The purpose of our study is to review our experience and suggest two-staged pedicled Latissimus Dorsi (LD) flap in fourth-degree burns of upper extremities. Methods: A retrospective review was performed from 2016 to 2019, on a total of 12 fourth-degree burn patients undergone two-staged pedicled LD flap surgery as reconstruction of upper extremities in our hospital. We reviewed the location of the injury, etiology, TBSA (%), size of burns requiring flap surgery, period from 1st surgery to secondary division surgery, complications. Results: Using two-staged LD flap as a primary reconstruction, the outcome is satisfactory. This flap preserves the elbow joint and maintains the length of the forearm. We obtain low donor-site morbidity, simplicity and a small incision in the donor site. Conclusion: Using two-staged LD flap in fourth-degree burns of upper extremity is effective, such as preserving elbow joint and maintaining the length of the forearm. Successful reconstruction was achieved with excellent cosmetic results with reducing a postoperative scar, donor-site morbidity. Due to these advantages, two-staged pedicled LD flap can be an optimal option for reconstruction of fourth-degree burns in the upper limb.