• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.253-256
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• 2009

In the micro turbojet engine less than 350kw power class, it is not easy to find out the good atomization fuel injector with good spray quality. However conceptually, rotating fuel injection system can give high atomization quality by only the centrifugal force of a high speed rotating shaft of the engine without high-pressure fuel pump. With this motivation, we manufactured very small rotating fuel injector of 40 mm diameter and performed under a variety of injection orifices. We measured droplet size, velocity and spray distribution by the PDPA(Phase Doppler Particle Analyzer) system. Also spray was visualized by using high speed camera. From the test results, we could understand that the length of liquid column from the injection orifice is mainly controlled by the rotational speeds. Furthermore, droplet size(SMD) is decreased with the rotational speeds and is influenced by the diameter of the injection orifice and liquid film thickness.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.512-512
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• 2017

날로 심각해지는 해수 오염, 유류사고, 해파리에 의한 인명피해 및 발전소의 경제적 피해사고, 해양 쓰레기 등과 같은 해양 환경 문제가 발생하고 있다. 이러한 해양환경문제를 해결하기위해 생물학적 방법과 물리적 방법이 있으나 생물학적 방법은 개체군과 종류의 변화로 그 적용이 어려운 실정이고, 물리적 방법은 지속적인 제거를 위한 비용적인 문제와 인부 및 자원봉사자의 안전문제가 발생한다. 따라서 에어버블을 이용한 각종 친환경적 방법이 주목받고 있다. 본 연구에서는 에어버블 차단막의 차단율을 증가시키기 위해 현장조건 내에서 에어버블의 거동특성에 대한 실험을 하였다. 실험을 위해 회류식 개수로 에어버블 거동실험장치를 제작하였다. 실험장치는 길이 8.1m, 높이 1.2m, 폭 0.7m이며, 두께 10mm의 투명 아크릴를 사용하여 에어버블의 거동을 관찰 할 수 있게하였다. 대형펌프를 사용하여 물이 회류함을 통해 흐름유속을 만들어 현장조건을 고려하였다. 에어버블을 분사하기 위해 압축공기 저장탱크와 연결된 분사구가 있으며, 노즐의 크기(0.5mm~1.0mm)로 분사량을 조절하고 분사압은 별도의 조절장치를 이용하여 0~5bar 범위의 분사압 조절을 가능하게 하였다. 초고속 카메라와 3축유속계를 사용하여 에어버블의 이동경로, 유속 및 에어버블의 거동을 측정하였다. 실험을 통한 구간별 에어버블의 거동 분석 결과, 상승속도는 분사구에서 분출되는 구간인 0~0.8m 에서는 상승속도가 증가하고, 0.8~1.2m구간에서는 속도가 다시 상승하는 경향을 확인하였다. 이는 수표면에 가까워질수록 수압이 작아져서 에어버블의 크기가 커짐에 따라 부력이 커짐으로 판단된다. 같은 이유로 분사량이 많을수록 상승속도도 같이 증가되는 것으로 나타났다. 유속에 따른 거동은 유속을 0.1m/s~0.5m/s로 조정하여 유속별 에어버블이 수표면까지 도달하는 거리, 속도 및 이동경로를 분석하였다. 유속과 에어버블이 수표면까지 도달하는 거리는 비례하여 증가하는 것을 확인하였다. 실험결과를 바탕으로 조건에 따른 에어버블 거동 경험식을 도출하였다. 본 실험은 회류식 개수로 에어버블 거동실험장치를 활용하여 에어버블 거동 경험식을 제시하였으며, 이를 바탕으로 에어버블 차단막 기술 개발을 위한 기초자료로 이용될 수 있을 것이다.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1034-1042
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• 2012

This study was performed by using an LFR (laminar flow reactor), which can be used to carry out different types of research on coal. In this study, an LFR was used to analyze coal flames, tar and soot yields, and structures of chars for two coals depending on their volatile content. The results show that the volatile content and oxygen concentration have a significant effect on the length and width of the soot cloud and that the length and width of the cloud under combustion conditions are less than those under a pyrolysis atmosphere. At sampling heights until 50 mm, the tar and soot yields of Berau (sub-bituminous) coal, which contains a large amount of volatile matter, are less than those of Glencore A.P. (bituminous) coal because tar is oxidized by the intrinsic oxygen component of coal and by radicals such as OH-. On the other hand, at sampling heights above 50 mm, the tar and soot yields of Berau coal are higher than those of Glencore A.P. coal by reacted residual volatile matter, tar and light gas in char and flame. With above results, it is confirmed that the volatile matter content and the intrinsic oxygen component in a coal are significant parameters for length and width of the soot cloud and yields of the soot. In addition, the B.E.T. results and the images of samples (SEM) obtained from the particle separation system of the sampling probe support the above results pertaining to the yields; the results also confirm the pore development on the char surface caused by devolatilization.

• Journal of Chest Surgery
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• v.38 no.10 s.255
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• pp.717-720
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• 2005

Here we report a case of posterior left ventricular (LV) free wall rupture following postinfarct ventricular septal rupture (VSR). A 58-year-old man was transferred to the hospital under the impression of acute myocardial infarction. Posterior VSR was seen on echocardiographic examination. The intraaortic balloon pump catheter was introduced percutaneously and the emergent operation was proposed. Sudden circulatory collapse was developed shortly after the anesthetic induction and the patient's chest was hurriedly opened while on cardiopulmonary resuscitation. The acute cardiac tamponade was seen and the blood was seen pumping from the longitudinal tear at the mid-level of LV posterior wall, measuring 2 cm in length. The cardiopulmonary bypass was set and LV reconstruction was done. The postoperative recovery was delayed due to the brain injury presumably caused by preoperative cardiac arrest.

• Clinical and Experimental Pediatrics
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• v.45 no.11
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• pp.1389-1396
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• 2002

Purpose : This study was done to analyze the changes in the clinical conditions and the diagnosis of hypertrophic pyloric stenosis. Methods : We report a retrospective clinical analysis of 39 patients with hypertrophic pyloric stenosis from Jan. 1992 to Aug. 2001. The age and sex distribution, family and birth history, clinical symptoms, the ultrasonographic and the operative sizes of pyloric canals were compared. Results : The body weight was below the 3 percentile at admission in eight cases(20.5%). "Olive like mass" in right upper quadrant was palpated during physical examination in 23 cases(59%) and gastric peristaltic wave observed in six cases(15%). The ultrasonographic measurements showed that the pyloric muscle thickness to be $4.95{\pm}0.99mm$($mean{\pm}SD$), pyloric diameter $14.42{\pm}2.64mm$, and pyloric length $20.17{\pm}3.92mm$. Fredet-Ramstedt pyloromyotomy was employed in all cases. The operative measurements of the pyloric muscle thickness was $5.11{\pm}1.01mm$, pyloric diameter $15.01{\pm}2.47mm$, and pyloric length $22.32{\pm}3.43mm$. Conclusion : There was no significant difference between the ultrasonographic and operative measurements. Currently, the hypertrophic pyloric stenosis patients showed lesser clinical hallmarks of the disease. The earlier diagnosis using imaging studies before development of significant metabolic abnormalities is becoming an important factor that change the future outcomes of hypertrophic pyloric stenosis.

• Ocean and Polar Research
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• v.36 no.1
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• pp.13-24
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• 2014

We established the first complete ice core processing method and analytical procedures for fundamental proxies, using a 40.2 m long ice core drilled on the Mt. Tsambagarav glacier in the Mongolian Altai mountains in July 2008. The whole core was first divided into two sub ice core sections and the measurements of the visual stratigraphy and electrical conductivity were performed on the surface of these sub core sections. A continuous sequence of samples was then prepared for chemical analyses (stable isotope ratios of oxygen ($^{18}O/^{16}O$) and hydrogen ($^2H/^1H$), soluble ions and trace elements). A total of 29 insoluble dust layers were identified from the measurement of visual stratigraphy. The electrical conductivity measurement (ECM) shows 11 peaks with the current more than 0.8 ${\mu}A$ Comparing the profiles of $SO_4{^{2-}}$ and $Cl^-$ concentrations to correlate with known volcanic eruptions, the first two ECM peaks appear to be linked to the eruptions (January and June 2007) of Kliuchevskoi volcano on the Kamchatka Peninsula of Russia, which supports the reliability of our ECM data. Finally, the composition of stable isotopes (${\delta}^{18}O$ and ${\delta}D$) shows a well-defined seasonal variation, suggesting that various chemical proxies may have been well preserved in the successive ice layers of Tsambagarav ice core. Our ice core processing method and analytical procedures for fundamental proxies are expected to be used for paleoclimate and paleoenvironmental studies from polar and alpine ice cores.