• 대한기계학회논문집A
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• 제35권5호
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• pp.487-494
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• 2011

LNG / LNG-FPSO선박에 사용되는 안전밸브는 배관 시스템으로부터 유체를 방출하여 시스템의 압력을 일정하게 유지시키는데 중요한 역할을 한다. 이러한 안전밸브의 기능적 특성으로 인해 유출계수는 밸브의 성능 중 가장 큰 비중을 차지하며, 선급의 인정을 받기 위해서는 0.8이상의 유출계수가 요구되고 있다. 밸브 성능을 향상시키기 위해서 밸브 내부에서 발생하는 유동특성에 대한 정확한 이해가 필요함에도 불구하고 대부분의 밸브 설계의 경우 현장 작업자들의 경험과 실험에 의한 시행착오에 의존하고 있다. 본 논문에서는 안전밸브에 대한 유동해석을 통해 밸브 내부에 발생하는 압축성 유동현상을 고찰하였고, 실험과 해석에 의한 유출계수를 비교하여 유동해석의 타당성을 검증하였으며, 안전밸브를 지나는 공기의 질량유량을 예측하기 위한 유동해석 모델을 확립하였다.

• 한국추진공학회지
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• 제7권4호
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• pp.33-38
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• 2003

플룸간섭 현상은 플룸에 의한 경계층 유동의 박리, 강한 전단층의 발생, 그리고 다수의 충격파들이 박리유동 및 전단층과 상호작용하게 되는 매우 복잡한 유동현상으로, 현재 미사일의 후미부에서 발생하는 플룸간섭 현상의 상세에 관해서는 잘 알려져 있지 않다. 본 연구에서는 초음속 미사일의 동체후미부에서 발생하는 플룸간섭 현상의 특징 및 동체기저부에 설치된 다공확장벽(porous extension)의 플룸간섭 현상에 대한 영향을 수치해석적으로 조사하였다. 그 결과, 다공확장벽이 플룸에 의한 충격파와 경계층 유동의 박리를 완화시켜 미사일 동체의 제어성능이 향상될 수 있음을 알았다.

• 한국환경과학회지
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• 제19권3호
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• pp.379-387
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• 2010

Sediments of Little Scioto (LS) River in Ohio was contaminated by poor disposal of creosote from Baker Wood Creosoting Facility. Among the primary compounds of creosote, Polycyclic Aromatic Hydrocarbons (PAHs) are the most common ingredient PAHs are known for toxic, carcinogenic and mutagenic compounds. There are many difficulties to remove the PAHs in nature environment because their characteristics are having a less water-solubility, volatile and low mobility properties as increasing the molecular weight. The generation of hydroxyl radicals (${\cdot}OH$) and hydrogen peroxide ($H_2O_2$) forms as well as high temperature (5000 K) and pressure (1000 atm) by a physico-chemical effects of ultrasound during a cavitation collapse can promote the degradation and desorption of PAHs in sediment And it can also produces shock wave and microjets which are able to change the size and surface of particle in solid-liquid system as one of physical effects. Therefore, we explored to understand the role of particle size, the effect of elimination for PAHs concentration by ultrasound and optimize the conditions for ultrasonic treatment. The condition of various size of particles (> $150{\mu}m$, < $150{\mu}m$) and solid-liquid ratio (12.5g/L, 25g/L) for the treatment was considered and ultrasonic power (430 W/L) with liquid - hexane extraction and microwave extraction method were applied after ultrasound treatment.

• 한국수산과학회지
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• 제35권6호
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• pp.563-567
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• 2002

Developing base data on luring fish schools into netting position by the use of underwater audible sound on japanese parrot fish Oplegnathus fasciatus found in the coastal waters of Jeju Island, S. Korea. Auditory threshold was determined by the heartbeat condition technique using pure tones coupled with a delayed electric shock. The audible range of japanese parrot fish extended from 80 Hz to 500 Hz with a peak sensitivity at 200 Hz. The mean auditory thresholds at the frequencies of 80 Hz, 100 Hz, 200 Hz,300 Hz and 500 Hz were 104 dB, 95 dB, 91 dB, 99 dB and 113 dB, respectively. As the frequency became higher than 200 Hz, the auditory threshold increased almost linearly with increasing frequency. Critical ratios of fishes measured in the presence of masking noise in the spectrum level range of 69$\~$78 dB (0 dB re 1$\mu$Pa/$\sqrt{Hz}$) ranged from 21 dB to 40 dB at test frequencies. The noise spectrum level at the start of masking was about 70 dB within the test frequency range. The sound pressure level of 100$\~$200 Hz recognized by japanese parrot fish under the ambient noise is above 91 dB and the critical ratio for them is above 21 dB.

• 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.

• 화약ㆍ발파
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• 제37권4호
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• pp.10-16
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• 2019

충격파나 압력파가 구조물에 미치는 영향을 평가하기 위해서는 과압, 양의 압력 지속시간, 충격량에 대한 정보가 필요하다. 본 연구에서는 증기운 폭발 해석에 효과적인 다중에너지법을 적용하여 과압 및 양의 압력 지속 시간을 결정하였다. 영국 Nypro 화학회사에서 발생한 싸이클로헥산 증기운 폭발 사고에서 추정된 총 폭발열을 기반으로 폭발원으로부터 40, 80, 120, 160, 200, 240, 280, 320, 360(m) 이격된 지점에서의 과압, 양의 압력 지속시간을 평가하였다. 거리에 따라 과압은 지수적으로 감소하는 것으로 나타났고, 양의 압력 지속시간은 거의 선형적으로 증가하는 것으로 나타났다. 상기의 각 거리에서 구한 과압 및 충격량을 이용하여 각 거리에서의 구조물의 손상 확률을 평가하기 위해서 프로빗 함수를 사용하였다. 손상 확률을 평가한 결과 120m 이내 지점에서는 붕괴의 가능성이 크고, 240m 이내에서는 심각한 구조물의 손상이, 구조물의 가벼운 손상과 유리창 파손은 전 범위에 걸쳐서 발생하는 것으로 나타났다.

• 동의신경정신과학회지
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• 제19권2호
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• pp.265-278
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• 2008

Stress reaction can be shown widely in the systems of psychology, endocrinology, immunology and so on. Stress promotes catecholamine from the autonomic nerve system, and this activates the sympathetic nerve system. As the sympathetic nerve system is activated, high blood pressure, tachycardia, vertigo, anxiety, diaphoresis, myotonic reaction and others can happen. Autonomic imbalance is the syndrome that people suffer from various symptoms accompanying no organic lesions and no psychological disorders by losing the hormonies between the sympathetic and parasympathetic nerve system. We experienced a 55 year-old female who complained of sudden abdominal pain after being frightened at trouble with her husband. Her abdominal pain was very characteristic, "Something is like rising in my abdomen.", that occurred several times a day. We diagnosed 'Bun-Ton Disease' from her abdominal sign. Several oriental medicine books recorded aspects of Bun-Ton disease and treatments, we had given herbal medicine and treated acupuncture be based on those. Results from studies to date suggest the Bun-Ton Disease's main cause is fright or shock, and they stimulate releasing epinephrine or norepinephrine, that result in various symptoms. In this case report, we will present this patient's case and review the Bun-Ton Disease.

• Toxicological Research
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• 제20권2호
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• pp.159-166
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• 2004

Safety pharmacological properties of CJ-11555, an anti-cirrhotic agent, were investigated in experimental animals and in vitro test system. CJ-11555 had no effects on normal body temperature in rats, motor coordination, chemoshock induced by pentetrazol, electric shock induced by electric shocker and writhing syndromes in mice at dose levels of 100, 300 and 1,000 mg/kg. CJ-11555 inhibited intestinal activity and prolonged hexobarbital-induced sleeping time in mice at the dose level of 1,000 mg/kg. CJ-11555 affected on general activity and behaviour tests in SD rats, such as lacrimation, ptosis, piloerection, decreased body tone, abnormal dispersion within the cage, diarrhoea, red colored faeces, slight hypothermia and decreased grooming, at the dose level of 1,000 mg/kg in rats. CJ-11555 was effected on cardiovascular and respiratory system in anesthetized beagle dogs, such as tachycardia, increase of mean blood pressure and decrease of PR interval, decrease of respiratory rate and minute volume, at dose levels of 10 and 30 mg/kg. However, these effects were also observed in vehicle treated anesthetized beagle dogs. In in vitro experiments, CJ-11555 inhibited agonists (histamine, acetyl-choline or $BaCl_2$) induced contraction of isolated guinea-pig at the concentration of 30$\times$$10^6$ M. CJ-11555 was weekly inhibited hERG channel current at concentrations of 10 and 30$\times$$10^6$ M, and $IC_{50}$ was estimated to be higher than 30${\times}$$10^6$M. Based on these results, it was concluded that CJ-11555 affected on cardiovascular and respiratory system, general activity and behaviour and hexobarbital-induced sleeping time at the dose level of 1,000 mg/kg and contraction of the smooth muscle and hERG channel current at the concentration of 30$\times$$10^6$ M.

• Journal of Chest Surgery
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• 제45권2호
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• pp.91-94
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• 2012

Background: Despite improved managements for acute respiratory distress syndrome (ARDS), its mortality remains high. Extracorporeal membrane oxygenation (ECMO) has emerged as the final option for the treatment of ARDS unresponsive to conventional measures. This study describes our experiences of venovenous ECMO support for the treatment of ARDS. Materials and Methods: Between 2007 and 2010, 56 patients (aged $56.6{\pm}13.4$ years, 43 males) received venovenous ECMO for the treatment of ARDS. The detailed clinical records were retrospectively reviewed. Results: Before the institution of ECMO support, 35 patients (55.4%) required nitric oxide inhalation, 35 patients (55.4%) received continuous renal replacement therapy, and 20 patients (35.7%) were in shock status. The median duration of ECMO support was 164 hours (range, 5 to 1,413 hours). 27 (48%) patients could be successfully weaned from ECMO. Of them, 7 (13%) survived to discharge. On logistic regression analysis, a requirement for higher inspiratory pressure before ECMO support was the only significant factor that could predict ECMO weaning failure. Conclusion: The outcome of venovenous ECMO support for the treatment of ARDS was suboptimal. Further improvements in outcomes should be made through the accumulation of experience and establishment of a standardized protocol for the management of ECMO.

• Journal of Chest Surgery
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• 제5권1호
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• pp.13-18
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• 1972

In 1835,Schlesinger first described a case of subisthmlc lower thoracic aortic coarctation. Since Olim`s unsuccessful reconstructive surgery in 1949 and Beattie`s first successful resection with homograft replacement on such a lesion in 1951 were reported,about 20 cases of atypical aortic coarctation had been treated by definitive surgery until 1964. In Korea, only 2 cases of atypical aortic coarctation treated by bypass graft were reported until now. This is the third case-report treated by reconstructive surgery. The patient,11 year old girl who had 2 year history of headache, visual weakness, intermittent claudlcation, and general weakness, was first diagnosed of having the hypertension due to atypical coarctation by the findings of high blood pressure[170/110mmHg] at the upper extremity and weak pulsation on both femoral artery,murmur on the epigastrium, absence of aortic knob, and aorto graphy. Aortography demonstrated the isolated segmental narrowing[length 5cm, diameter 0.4cm] at the level of aortic hiatus 2cm above celiac arterial origin, the dilated right 9th, 10th, 11th intercostal arteries with multiple dimunitive collaterals and no associated abnormalities in the other arteries. Preoperatlve positive findings were strong positive mantoux test, high AST[720 units]. transient mild cardiomegaly with right lung infiltration on chest X-ray and suggestive left ventricular hypertrophy on ECG. On December 1970, through separate left thoracotomy and abdominal approach, bypass graft between descending thoracic aorta and abdominal aorta below renal artery was performed. The operation was first successful with satisfactory reduction of hypertension on the upper trunk[postoperatlve 130/80mmHg] and strong pulsation on the lower extremities[postop. O, postop. 140/100mmHg]. However,6 weeks after surgery, she expired of sudden hemoptysis and shock due to anastomotic leak within the thorax. Operative finding disclosed that the affected aorta was firm, with rich periaortic fibrosis and the outer diameter of stenotic site was not attenuated. Histopathology of the resected specimen was also compatible with primary arteritis.