• 한국항공우주학회지
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• 제46권3호
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• pp.230-236
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• 2018

Anti-G 밸브는 Anti-G Suit에 연결되어 급격한 기동 시 조종사에게 적절한 여압기능을 제공한다. 또한 Anti-G 밸브는 연결된 레귤레이터를 조종하여 기동 간 조종사의 생리학적 산소요구량 증가에 따라 적절한 PBG(Pressure Breathing for G)가 제공되도록 조절한다. FA-50과 같이 고기동 임무가 요구되는 항공기에서 Anti-G 밸브는 조종사의 생존 및 항공기의 안전을 위해 매우 중요한 요소이다. 본 논문에서는 Anti-G 밸브 개발 중 발생된 문제점을 바탕으로 개발 요구도 및 설계개선 내용을 기술하였으며, 개선된 연구에 대해 구성품 성능시험 및 비행시험검증 결과를 함께 소개한다.

• Korean Circulation Journal
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• 제54권1호
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• pp.43-56
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• 2024

Background and Objectives: The therapeutic strategy for inflammation and degenerative calcification is of utmost importance for bioprosthetic heart valve (BHV) implanted patients. The purpose of this study was to compare the anti-inflammatory and anti-calcification effects of Entelon150^® (grape seed extract), losartan, and rosuvastatin, in a rabbit model of intravascular BHV leaflet implantation in bovine pericardium. Methods: A total of 28 rabbits were implanted with BHV leaflet in the external jugular veins. The Entelon150^® group was administered 7.7 mg/kg Entelon150^® twice daily for 6 weeks after surgery. The losartan and rosuvastatin groups received 5.14 mg/kg and 1 mg/kg, respectively, once per day. The control group received 1 ml of saline once daily. And then, calcium concentration was measured in the implanted BHV, and histological and molecular analyses were performed on the surrounding tissues. Results: The calcium content of the implanted tissue in the Entelon150^® group (0.013±0.004 mg/g) was lower than that in the control group (0.066±0.039 mg/g) (p=0.008). The losartan (0.024±0.016 mg/g, p=0.032) and rosuvastatin (0.022±0.011 mg/g, p=0.032) groups had lower calcium content than the control group, and higher tendency than the Entelon150^® group. Immunohistochemistry revealed that the expressions of bone morphogenic protein 2 (BMP2), S-100, and angiotensin II type 1 receptor in the Entelon150^® group showed lower tendency than those in the control group. The protein expression levels of BMP2 were reduced in the Entelon150^® group compared with those in the control group. Conclusions: Entelon150^® exhibited a significant effect, similar to other drugs, in reducing calcification and inflammation in the intravascular bovine pericardium.

• 한국자동차공학회논문집
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• 제5권5호
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• pp.20-26
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• 1997

A System for reducing vehicle body roll by active control is developed. The stabilizer bar with hydraulic rotary actuator produces anti-roll moment which suppresses roll tendency. This reduction of roll improves the driving safety as well as the ride comfort. Vehicle test data shows considerable reduction of roll angle during steady-state turning. Also improvement of ride comfort is achieved by making the actuator freely rotatable, i.e. by connecting all chambers of actuator in normal driving conditions. A control algorithm using steering wheel angle and vehicle speed signal as input valve is applied. It is compared with signal of the G-sensor.

• 한국항공우주학회지
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• 제43권6호
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• pp.548-556
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• 2015

F-22, F-16 및 F-15와 같은 고성능 전투기는 전투성능의 극대화를 위해 고기동성(highly maneuverable)을 보유하고 있다. 이로 인해 고기동 시에 조종사는 고중력가속도(high gravity acceleration)에 노출되고 피로도(fatigue)의 증가로 임무효율의 저하가 발생하며, 심할 경우에는 의식상실(Gravity-induced Loss Of Consciousness, GLOC)에 직면할 수 있다. 선진 항공업체에서는 조종사가 고중력가속도에 견딜 수 있는 내성을 향상시켜 의식상실에 진입하는 것을 방지하는 다양한 기술을 항공기에 적용하고 있다. 특히, 가속도방호복(Anti-G Suit)은 GLOC으로 인한 의식 상실을 방지할 수 있을 뿐만 아니라, 전투 기동 시에 조종사의 피로를 감소시킴으로써 임무성공률을 향상시킬 수 있다. 본 논문에서는 초음속 고등훈련기 모델을 기반으로 하여 고기동 시에 중력가속도의 증가에 따라 AGS에 최적의 공기압을 제공할 수 있는 제어알고리즘을 개발하고 검증하였다. 이러한 결과는 추후에 체계개발이 진행될 한국형전투기개발사업(Korean Fighter eXperimental, KF-X)에서 핵심기술을 개발하는데 기여하리라 기대한다.

• Journal of Periodontal and Implant Science
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• 제51권4호
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• pp.226-238
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• 2021

Purpose: Although several reports have described the relationship between periodontal disease and cardiovascular disease, information about the association between periodontal disease and the progression of degenerative aortic stenosis (AS) is lacking. Therefore, we performed a retrospective, single-center, pilot study to provide insight into this potential association. Methods: Data from 45 consecutive patients (19 men; median age, 83 years) with mild or moderate degenerative aortic stenosis were analyzed for a mean observation period of 3.3±1.9 years. The total amount of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis and titers of serum immunoglobulin G (IgG) against periodontal bacteria and high-sensitivity C-reactive protein (hs-CRP) were evaluated. Aortic valve area (AVA), maximal velocity (Vmax), mean pressure gradient (mean PG), and the Doppler velocity index (DVI) were evaluated. The change in each parameter per year ([Parameter_LATEST-Parameter_BASELINE]/Follow-up Years) was calculated from the retrospective follow-up echocardiographic data (baseline vs. the most recently collected data [latest]). Results: No correlation was found between the concentration of periodontopathic bacteria in the saliva and AS status/progression. The anti-P. gingivalis antibody titer in the serum showed a significant positive correlation with AVA and DVI. Additionally, there was a negative correlation between the anti-P. gingivalis IgG antibody titer and mean PG. The hs-CRP concentration showed positive correlations with Vmax and mean PG. Meanwhile, a negative correlation was observed between the anti-P. gingivalis IgG antibody titer and ΔAVA/year and Δmean PG/year. The hs-CRP concentration showed positive correlations with Vmax and mean PG, and it was significantly higher in patients with rapid aortic stenosis progression (ΔAVA/year <-0.1) than in their counterparts. Conclusions: Our results suggest that periodontopathic bacteria such as A. actinomycetemcomitans and P. gingivalis are not directly related to the status/progression of degenerative AS. However, inflammation and a lower immune response may be associated with disease progression.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(2)
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• pp.562-567
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• 1995

The concept of VLDT (Variable Low DNBR Trip), a new CPC trip function, was proposed and applied to the events of increase in secondary heat removal, such as an excess feedwater event anti an IOSGADV (Inadvertent Opening S/G Atmospheric Dump Valve). Major assumption used in this study was no time delay to LOOP (Loss of Offsite Power) after turbine trip. In case of using this VLDT function, safety criterion of DNB would not be violated under the same condition as previous analysis without any change in thermal margin.

• Journal of Chest Surgery
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• 제33권8호
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• pp.648-654
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• 2000

Background: Cardiopulmonary bypass during open heart surgery causes systemic inflammatory respose. IL-10 is an anti-inflammatory cytokine that inhibits inflammatory process and protects organ function by down regulation of pro-inflammatory cytokine release and maintenance of blood level balance with pro-inflammatory cytokines. Mateial and Method: Plasma IL-10 levels were measured and analyzed in 22 patients who underwent open heart surgery (11 cases of coronary artery bypass graft, 11 cases of valve replacement) under cardiopulmonary bypass since 1988 January to July at Department of Thoracic and Czardiovascular surgery, Yeungnam University Hospital. 1g of methylprednisolone was administrated to thirteen patients randomly. Blood samp.es were taken and collected at the time of induction of anesthesia, 10 min before cardiopulmonary bypass, 10 min after starting of CPB, 10 min aftr aortic cross clamping, 10 min after ACC release, and 10 min, 2 hours, and `5 hours after CPB respectively. The plasma levels of IL-10 were determined by enzyme-linked immunosorbent assays(ELISA). Wilcoxon-Raule Sum test was used for statistical analysis. Result: In all 22 patients, cardiopulmonary bypass time was used for statistical analysis. Result: In all 22 patients, cardiopulmonary bypass time was 171$\pm$41.4 min and aortic cross clamp time was 118$\pm$36.5 min. Peak IL-10 level was achieved at 10 min after ACC(361.0$\pm$52.81pg/ml) and was decreased sharply at 2 hours after CPB. Peak IL-10 level was correlated positively with aortic cross clamp time(p=0.011); however, it did not correlated with bypass time(p=0.181). In valve replacement group, mean IL-10 level at peak point was 567.89$\pm$107.69 pg/ml and was significantly higher than that of coronary artery bypass group(205.67$\pm$192.70 pg/ml)(p<0.001). ACC time in valve replacement group was significantly longer than that of coronary artery bypass group(p<0.01), however, bypass time was not(p=0.212). Thirteen patients with steroid pretreatment before starting of CPB showed relatively higher plasma IL-10 level than in control group, however, no statistical significance was noted(p=0.19). Conclusion: plasma level of IL-10 was increased in association with cardiopulmonary bypass and revealed peak at 10 min after ACC release. IL-10 level was correlated positively with ACC time. Therefore, systemic inflammatory respeonse in association with cardiopulmonary bypass could be decreased by reducing ACC time during cardiac surgery.