• 한국추진공학회지
• /
• 제17권5호
• /
• pp.37-46
• /
• 2013

2상유체 동축형 다공성재 분사기는 중심포스트에서 분사되는 액체제트 주위로 형성된 다공성재 실린더의 내부 표면에서 기체를 반경방향으로 분사한다. 동축형 다공성재 분사기의 추진제 혼합비에 따른 연소성능을 분석하기 위하여 에탄올/아산화질소 추진제를 사용한 단일 축소형 분사기의 연소시험이 수행되었으며, 수집된 데이터 및 계산된 성능인자들에 대하여 불확실도 해석이 이루어졌다. 연소시험에 의한 추진제 혼합비에 따른 특성속도 경향은 CEA 이론값과 유사하였으나 최대값을 가지는 혼합비 영역이 이론혼합비영역에 가까웠다. 특성속도효율은 산화제 과잉 영역으로 갈수록 더 높게 나타났다.

• 한국추진공학회지
• /
• 제19권3호
• /
• pp.47-53
• /
• 2015

이론성능해석을 통하여 메탄/산소 이원추진제 소형로켓엔진의 형상설계에 필요한 설계인자들을 도출하였다. 로켓엔진의 이론성능 분석을 위해 CEA를 이용하였고, 추력실 내부의 화학반응을 화학평형 상태로 가정하여 엔진의 형상설계에 필요한 최적의 추진제 혼합비, 특성길이, 최적 팽창비 등을 도출하였다. 인젝터의 경우, 미립화 성능이 우수하고, 다른 인젝터 형상에 비해 연소효율이 높은 스월 동축 인젝터를 설계하였다. 노즐형상은 80%의 길이를 갖는 벨형 노즐을 설계하였고, 추력실 내부압력 1.72 MPa, 총 추진제 질량유량 0.18 kg/s, O/F ratio 2.7일 때의 지상연소시험용 로켓엔진의 형상설계 결과를 제시한다.

• Journal of Korean Neurosurgical Society
• /
• 제30권3호
• /
• pp.284-294
• /
• 2001

Objective : Stroke is leading cause of death and more importantly it is cause of serious disability. The effective treatment of acute ischemic stroke still remains a challenge to modern medicine. Recent clinical trials have shown that carotid endareterctomy(CEA) provide overwhelming benefits compared with medical therapy in preventing subsequent stroke for symptomatic carotid stenosis. For the asymptomatic ones, the data are less compelling, but highly suggestive that CEA do have benefits in properly selected patients. Materials and Methods : To investigate the clinical manifestations of carotid stenosis and results of CEAs, authors analyzed retrospectively 19 CEAs in 16 patients from June 1986 to June 1999. Age of patients ranged from 55 to 76 years(median, 66) and male to female ratio was 14 to 2. The duration of follow-up was 1 to 144 months (median, 26). All of CEAs were done on the side of stenosis more than 80% and bilateral CEAs were done in three. Six CEAs were performed in asymptomatic patients. Results : Seventeen of 19 CEAs showed excellent results and complication rate was low although ipsilateral ischemic stroke occurred in two. Conclusion : CEA may be a valuable surgical treatment for ischemic stroke caused by carotid stenosis and also for prevention of stroke of asymptomatic patients with carotid stenosis.

• Asian Pacific Journal of Cancer Prevention
• /
• 제17권3호
• /
• pp.939-944
• /
• 2016

Background: Cell-free DNA circulating in blood is a candidate biomarker for malignant tumors. Unlike uniformly truncated DNA released from apoptotic non diseased cells, DNA released from necrotic cancer cells varies in size. Objectives: To measure the DNA integrity index in serum and the absolute DNA concentration to assess their clinical utility as potential serum biomarkers for colorectal carcinoma (CRC) compared to CEA and CA19-9. Materials and Methods: Fifty patients with CRC, 10 with benign colonic polyps and 20 healthy sex and age matched volunteers, were investigated by real time PCR of ALU repeats (ALU q-PCR) using two sets of primers (115 and 247 bp) amplifying different lengths of DNA fragments. The DNA integrity index was calculated as the ratio of q-PCR results of ALU 247/ALU 115bp. Results: Serum DNA integrity was statistically significantly higher in CRC patients compared to the benign and control groups (p<0.001). ROC curves for differentiating CRC patients from normal controls and benign groups had areas under curves of 0.90 and 0.85 respectively. Conclusions: The DNA integrity index is superior to the absolute DNA concentration as a potential serum biomarker for screening and diagnosis of CRC. It may also serve as an indicator for monitoring the progression of CRC patients. Combining CEA and CA19-9 with either of the genetic markers studied is better than either of them alone.

• 한국추진공학회지
• /
• 제22권3호
• /
• pp.90-96
• /
• 2018

고체 점화제 $BKNO_3$는 항공우주 및 유도탄 등의 점화제로 널리 적용되는데 본 연구에서는 $BKNO_3$의 제조공정과 특성평가를 수행하였다. 이 고체 점화제는 금속분말과 산화제 그리고 유기 고분자물질(결합재)로 구성된다. 증발법(evaporation process)을 사용하여 원료들을 균질하게 혼합하였다. CEA 프로그램을 사용하여 $BKNO_3$의 물질특성 및 열적 반응 해석을 통한 최적 조성비를 설계하였으며, 입도, 형상, 감도, 열량 분석 등의 특성 평가를 수행하여 결과를 분석하였다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
• /
• pp.433-439
• /
• 2017

고체 점화제 $BKNO_3$는 항공우주 및 유도탄, 자동차 산업 등에 점화제로 널리 적용되는데 본 연구에서는 $BKNO_3$의 제조공정 과 특성평가를 수행하여 정리하였다. PMD에 사용되는 고체 점화제는 보통 금속분말과 산화제 그리고 유기 고분자물질(결합재)로 구성되며, 이들 원료들을 균질하게 혼합하기 위하여 본 연구에서는 증발법(evaporation process)를 사용하여 원료를 제조하였다. 원료 물질의 특성 및 열적 반응 해석(CEA Program)을 통한 최적 조성비를 설계하였으며, 이들의 입도/형상/감도/열량 분석 등의 특성 평가를 수행하여 결과를 비교 분석하였다.

• Journal of Chest Surgery
• /
• 제55권6호
• /
• pp.462-469
• /
• 2022

Background: Carotid endarterectomy (CEA) is used to treat carotid stenosis, which is associated with cerebral infarction and may result in neurologic deficits such as stroke, transient ischemic attack (TIA), and local nerve injury. To decrease surgery-related complications and improve patient satisfaction with esthetic outcomes, efforts have been made to minimize incision size instead of using a standard longitudinal incision. Methods: We performed a retrospective analysis of 151 cases of CEA, of which 110 used conventional incisions and 41 used high mini-skin incisions (HMIs), from March 2015 to December 2021 at a single institution. Short-term (30-day) postoperative results were evaluated for rates of mortality, stroke, TIA, and cranial/cervical nerve injuries. Risk factors for nerve injury were also assessed. Results: The HMI group showed significantly (p<0.01) shorter operative and clamp times than the conventional group. The HMI group also had significantly shorter incision lengths (5.3±0.9 cm) than the conventional group (11.5±2.8 cm). The rates of stroke, TIA, and death at 30 days were not significantly different between the 2 groups. There was no significant difference in the rate of cranial and cervical nerve injuries, and all injuries were transient. A high lesion level (odds ratio [OR], 9.56; 95% confidence interval [CI], 3.21-28.42; p<0.01) and the clamp time (OR, 1.07; 95% CI, 1.03-1.12; p<0.01) were found to be risk factors for nerve injuries. Conclusion: Use of the HMI in CEA for carotid stenosis was advantageous for its shorter operative time, shorter internal carotid artery clamp time, reduced neurologic complications, and improved esthetics.

• Journal of Yeungnam Medical Science
• /
• 제40권3호
• /
• pp.259-267
• /
• 2023

Background: Malnutrition and impaired immune responses significantly affect the clinical outcomes of patients with atherosclerotic stenosis. The Controlling Nutritional Status (CONUT) score has recently been utilized to evaluate perioperative immunonutritional status. This study aimed to evaluate the relationship between immunonutritional status, indexed by CONUT score, and postoperative complications in patients undergoing carotid endarterectomy (CEA). Methods: We retrospectively evaluated 188 patients who underwent elective CEA between January 2010 and December 2019. The preoperative CONUT score was calculated as the sum of the serum albumin concentration, total cholesterol level, and total lymphocyte count. The primary outcome was postoperative complications within 30 days after CEA, including major adverse cardiovascular events, pulmonary complications, stroke, renal failure, sepsis, wounds, and gastrointestinal complications. Cox proportional hazards regression analysis was used to estimate the factors associated with postoperative complications during the 30-day follow-up period. Results: Twenty-five patients (13.3%) had at least one major complication. The incidence of postoperative complications was identified more frequently in the high CONUT group (12 of 27, 44.4% vs. 13 of 161, 8.1%; p<0.001). Multivariate analyses showed that a high preoperative CONUT score was independently associated with 30-day postoperative complications (hazard ratio, 5.98; 95% confidence interval, 2.56-13.97; p<0.001). Conclusion: Our results showed that the CONUT score, a simple and readily available parameter using only objective laboratory values, is independently associated with early postoperative complications.

• 한국추진공학회지
• /
• 제20권3호
• /
• pp.25-31
• /
• 2016

본 연구에서는 항공우주, 유도탄, 자동화 산업에 널리 적용되는 금속복합화약 ZPP(Zirconium Potassium Perchlorate)의 제조공정 과 특성평가를 고찰하였다. 기본적으로 PMD에 사용되는 고체 점화제는 금속연료와 산화제 그리고 유기 고분자물질(결합재)로 구성되며, 이들 원료들을 균질하게 혼합하기 위하여 precipitation process를 사용하였다. 원료 물질의 특성 및 열적 반응 해석을 통한 최적 조성비를 설계하였으며, 이들의 입도, 형상, 열량 분석 등의 특성 평가를 수행하여 결과를 비교하였다.

• 한국추진공학회지
• /
• 제20권5호
• /
• pp.84-89
• /
• 2016

THPP (Titanium Hydride Potassium Perchlorate)는 산화제로 potassium perchlorate, 금속원료로 titanium hydride, 결합제로 Viton을 사용한 점화제이다. THPP는 항공우주 유도탄, 자동화 산업 등 널리 사용되고 있다. 본 연구에서는 PMD (Pyrotechnic Mechanical Device)에 사용되는 THPP의 제조공정 및 형상/열량/압력값과 같은 특성을 분석하였다. 또한 CEA 프로그램으로 조성비를 설계하였다.