• 한국전산유체공학회지
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• 제12권2호
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• pp.46-52
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• 2007

An experimental and numerical investigation of the ejector-jets focusing on its geometric parameters that effect on thrust performance was carried out. The area ratio of the primary nozzle that was tested in the present study was 2.17 and 3.18, while the ratio of the length to the diameter of the duct downstream the primary nozzle inlet had values of 3.41, 6.82, and 10.23. Internal flow properties of ejector-jet were estimated by comparison experiment data and CFD analysis for basic study of ejector-jet thrust performance. For examination of thrust performance, the thrust ratios increased with increase in L/D. Especially at AR=2.17, the maximum thrust augmentation was 33 percent for the shortest L/D. It is expected that the increase of mixing duct length of ejector-jet will be helpful in a thrust performance by improving mixing efficiency.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 춘계 학술대회논문집
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• pp.166-170
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• 2007

An experimental and numerical investigation of the ejector-jets focusing on its geometric parameters that effect on thrust performance was carried out. The area ratio of the primary nozzle that was tested in the present studywas 2.17 and 3.18, while the ratio of the length to the diameter of the duct downstream the primary nozzle inlet had values of 3.41, 6.82, and 10.23. Internal flow properties of ejector-jet were estimated by comparison experiment data and CFD analysis for basic study of ejector-jet thrust performance. For examination of thrust performance, the thrust ratios increased with increase in L/D. Especially at AR=2.17, the maximum thrust augmentation was 34 percent for the shortest L/D. It is expected that the increase of mixing duct length of ejector-jet will be helpful in a thrust performance by improving mixing efficiency.

• Journal of Pharmaceutical Investigation
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• 제17권1호
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• pp.15-21
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• 1987

Effects of phenobarbital pretreatment on the pharmacokinetics of enterohepatic recirculating griseofulvin were investigated by comparing normal to bile duct cannulated rats and also the effects of enhanced endogeneous bile flow on the absorption of griseofulvin were studied by means of in situ recirculation method in phenobarbital-pretreated rats. Phenobarbital was administered orally for five days at the dose of 75 mg/kg/day. The influence of phenobarbital pretreatment on the absorption rate constant, area under the plasma concentration-time curve, maximum plasma concentration of orally administered griseofulvin was not found in bile duct cannulated rats. Decreased absorption clearance and apparent partition coefficient of griseofulvin in accordance with the amount of endogeneous bile juice seemed to be due to the decrease of thermodynamic activity of griseofulvin as bile forms the micelle with griseofulvin.

• 한국항공운항학회지
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• 제30권1호
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• pp.12-19
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• 2022

The exhaust wake of an aircraft engine is discharged in a high temperature and high speed, which can damage objects such as an aircraft in the rear. The exhaust wake can lift small foreign substances lying on the ground or falling off, and the floating foreign substances can enter the intake duct of the aircraft moving from the rear and cause engine FOD (Foreign Object Damage). This study experimentally analyzed how the engine exhaust wake generated from military jet fighters affects the movement of foreign substances and evaluated the effects of foreign substances on the damaged area by measuring wake velocity. The simulation and field experimental results confirmed that the effect of exhaust wake increases as the rear position closer, and that foreign substances lifted by the wake can act as FOD to the adjacent rear aircraft.

• 한국분무공학회지
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• 제26권4호
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• pp.182-188
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• 2021

In this paper, using a transfer function-based analytical model, major factors influencing the acoustics and combustion instability in a two-stage duct system composed of a nozzle and a combustor were derived and their quantitative effects were evaluated. From the acoustic analysis, it was confirmed that the change in reflection coefficient and mean flow could have a great influence on the instability growth rate, and the area ratio and speed of sound ratio between the nozzle and the combustor are also key parameters to determine combustion instability as well as flame transfer functions.

• 한국지리정보학회지
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• 제14권4호
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• pp.1-12
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• 2011

도시 팽창과 신도시 개발로 도로, 전기, 상하수도 등의 7대 지하시설물의 안전에 대한 관심이 대두되고 있다. 특히 상하수도, 가스관 등을 수용하고 있는 공동구 설치 및 관리 방법이 대안으로 제시되고 있으나, 기존 공동구 시설은 국가 보안지역으로 묶여 관련 관리 기술에 대한 연구가 많이 이루어지지 못하였다. 특히 기존 인력에 의존하여 운영하는 현 방식은 실시간으로 긴박하게 발생하는 사건 사고에 적절히 대처하기 어려울 뿐만 아니라, 공동구내부에 화재 발생이나 가스유출 사고 발생 시 접근조차 불가능하며 사고에 대한 상황파악이나 대처가 어렵다. 그러므로 본 연구에서는 한국건설기술연구원내 설치되어 있는 실증실험장(TestLab)내에 설치되어 있는 공동구에서 무인 모니터링 장치를 설치하는 방법과 상수도관을 중심으로 시설물 관리 방법과 전체 모니터링을 위한 CCTV 영상 자료 처리 방법을 제안하고자 한다. 본 기술의 적용은 공동구내부에 실시간 모니터링이 가능하며, 사건 사고 발생 시 신속한 접근 및 대처가 가능하다.

• 대한의용생체공학회:의공학회지
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• 제20권1호
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• pp.29-36
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• 1999

본 연구는 목적은 PIV 시스템을 이용하여 분기관내 유동현상을 가시화하여 분기부 영역의 유동특성을 분석하는데 있다. PIV 시스템으로 유동장을 가시화하기 위해서 분기관 모델은 투명 아크릴판으로 제작하였고 작동유체와 추적입자는 각각 물과 송화가루를 사용하였다. 유동장에서 획득된 영상으로부터 속도벡터를 얻기 위해서 입자추적방법의 1-프레임 법과 2-프레임 법, 상호상관 PIV법인 2-프레임법을 사용하였다. PIV 시스템으로 측정된 실험결과의 신뢰성을 확보하기 위해서 표면구동 캐비티 유동의 속도분포를 4-프레임법으로 얻어진 기준 실험 데이터와 비교하였다. 분기관에서 뉴턴유체의 유동현상을 효과적으로 가시화하는데 필요한 상호상관 PIV방법의 2-프레임법을 적용하는 알고리즘을 개발하였고, sub-pixel과 면적보간을 사용하여 오벡터를 제거후 최종속도벡터를 얻었다. PIV를 이용한 분기관내 유동가시와 실험결과를 신뢰할 수 있는 수치해석 결과를 이용하여 검증한 결과 PIV 실험으로 얻어진 속도벡터는 수치해석의 결과와 잘 일치하였다. PIV 실험과 수치해석 결과로부터 분기관모델의 분기점 원위부에 재순환영역이 형성됨이 확인되었고 두 다른 방법을 이용한 재순환영역의 길이와 높이는 거의 동일하였다.

• 환경생물
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• 제33권2호
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• pp.93-97
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• 2015

The goniadid species, Glycinde bonhourei Gravier, 1904, is newly reported with the description and illustration from Korean waters. Our Korean materials of G. bonhourei have the following characteristics that are generally known as distinctive features from its congeners: the area II-1 on proboscis possesses unidentate papillae bearing broad base; the area IV on proboscis bears the papillae of duct's foot-shaped with rounded teeth; the area V on proboscis has straightly conical papillae bearing slightly bifid tip; 4-16 micrognaths are arranged on the dorsal side; all parapodia have one neuropodial presetal lobe; uniramous parapodia are present on 19-26 anterior segments. As a result of the present study, the genus Glycinde is newly reported from Korean waters.

• 치과방사선
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• 제25권2호
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• pp.561-567
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• 1995

Pleomorphic adenoma is a benign salivary gland tumor with histologic diversity. The majority of these tumor occurs in the parotid gland. The authors experienced the patients, who complained the tumor-like soft tissue mass on the palatal area. After careful analysis of clinical, radiological and histopathological findings, we diagnosed it as pleomorphic adenoma in the palatal area, and obtained characteristic features were as follows: 1. Main clinical symptom was a painless, slow growing, soft tissue mass with normal intact overlying mucosa on the palatal area. 2. In the radiographic examminations, well encapsulated homogeneous soft tissue mass was shown in the lesion site, and cortical thinning on the palate was also observed. 3. In histopathologic examminations, proliferated cellular components in the hyaline stroma were observed as double layered duct-like structure and densely solid sheet appearance.

• 대한의생명과학회지
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• 제19권2호
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• pp.158-163
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• 2013

Cholestatic liver is associated with hepatic inflammation and elevated proinflammatory cytokines. Recent studies indicate that certain cytokines can modulate bile secretion. In the present study, we have examined the role of interleukin (IL-2) on the bile secretion by a combination of study models. To examine the relevance of IL-2 on bile secretion, the expression of IL-2 and IL-2 receptor (IL-2R) of isolated normal and bile duct ligated (BDL) rats cholangiocytes was first measured by RT-PCR. In BDL rats, the expression of IL-2 and IL-2R was significantly increased compared with normal rats. To study the effect of IL-2 on bile secretion, bile flow was measured in normal and BDL rats. At the level of cholangiocytes, secretory responses of isolated bile duct unit (IBDU)s were quantified by videomicroscopy. The administrations of IL-2 had no significant effect on basal bile secretion in normal and BDL rats. There was no significant effect of IL-2 on basal bile ductular secretion as evidenced by no significant difference in luminal area of the IBDUs perfusedwith 100 pM of IL-2 from those of albumin carrier control. However, the secretin-stimulated bile ductular secretion was significantly (P < 0.01) inhibited by $34{\pm}4%$ (normal, n = 12), $21{\pm}5.3%$ (BDL 2 wk, n = 12) and $15{\pm}5.2%$ (BDL 4 wk, n = 12) with the co-administration of IL-2. As with other cytokines, physiologically relevant concentration of IL-2 can significantly inhibit secretin-stimulated bile ductular secretion. These findings support the important roles of cytokines in modulating bile secretion and may contribute to the cholestasis seen in cholestatic liver diseases.