• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.80-80
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• 1994

세라믹막을 이용한 oil 폐수 처리의 기초 연구로서 정밀여과용 세라믹막의 제조와 oil(kerosene)-in-water 타입 에멀젼에 대한 막분리 효율이 연구되었다. 정밀여과 막으로서는 압출(extrusion)법으로 성형하여 제조한 $\alpha$-알루미나 튜브(평균 기공크기 0.9 $\mum$)와 이들 튜브(담체)내부에 $ZrO_2$ 또는 $Al_2O_3$ 다공성 박막을 코팅한 2층 구조의 복합막들을 사용하였다. 담체의 높은 투과율 ($1700 l/m^2\cdot h$ at $\Deltap = 1$ atm)을 어느정도 유지하면서 막분리 효율을 증대시킬 수 있는 새로운 슬러리 코팅법이 개발되엇으며, 코팅후 950-1300$\circ$C 에서 열처리한 코팅층의 두께와 평균 기공크기는 각각 5 - 20 $\mum$정도 이었다. 정밀여과막의 특성평가를 위하여 막 제조조건에 따른 코팅층의 두께 및 결함유무를 SEM으로 일단 관찰한 후에 Bubble Point Test와 Mercury Porosimeter를 이용하여 측정한 최대 및 평균 기공반경과 물의 투과량으로부터 막 전체에 대한 결함 유무와 결함의 허용한도등을 비교 분석하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.795-801
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• 2004

An experimental study has been carried out to examine heat-transfer characteristics of an axisymmetric, under-expanded, sonic jet impinging on a flat plate and the local measurement of surface pressures and heat transfer coefficients on a plate have been achieved together with a visualization test of shock structure in a jet. As a result, it has been found that the Nusselt number distribution has different aspects depending on the under-expansion ratios and the nozzle-to-plate distances.

• Journal of the Korean Society of Marine Environment & Safety
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• v.4 no.1
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• pp.49-56
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• 1998

The Microfiltration and Ultrafiltration were used to treat effluent of secondary municipal wastewater treatment system(Sequencing Batch Reactor). The cross-flow hollow fiber, UF 500,000(NMWC) and MF 0.65$\mu$ membrane were selected as suitable membrane. Short term and long term fouling effect were measured as a factor of flux decrease and the fouling removal effect of mixing air bubble in the penetrant was studied. The removal of anionic sulfactants before and after formation of micelle with several kinds of oil were checked. The test results show that removal of TOC was 70~80%, TN 28% and TP 16%. The decrease of flux due to fouling were 85%(UF) and 90%(MF) after running of 100hrs. The removal of anionic sulfactants were 60~70% notwithstanding micelle or not.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.37-38
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• 2011

This study is to analyze and compare improved curing sheet with blue sheet in order to verify the performance related to tensile stress. As results, it is confirmed that improved curing sheet(MP+BBS1) is better than the blue sheet at using field already. Synthetically, curing sheet improved by MP is analyzed to be available instead of the original because it is superior to tensile stress.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1152-1166
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• 2023

The bubbly flow of air or steam in subcooled water are investigated here in several test cases, characterized by different pipe sizes, bubble dimensions and flow rates, by means of CFD using a Eulerian-Eulerian approach. The performance of models that differ for the turbulence closure in the continuous phase, as well as for the description of the lift force on the dispersed phase, are compared in detail. When air is considered, the space of the experimental parameters leading to a reasonable performance for the selected models are identified and discussed, while the issues left in the modelling of the concurrent condensation are highlighted for the cases where steam is used.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.2
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• pp.146-153
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• 2015

An unmanned aerial photography method by using an unmanned helicopter is useful method for measuring of the water-entry traces of small falling objects into the sea. Pixel sizes on the aerial photograph may be too large due to a limit of camcorder resolution and a wide shooting area. If the pixel size is too large, identification of water-entry trace is impossible. Thus an accurate prediction of water-entry trace size is required. The traces of water-entry could be classified into three types such as splash, water column, and bubble. Diameters of each trace are predicted by water-entry impact pressure theories, cavity theories, and trial test results. The results are verified by drop tests using an unmanned helicopter at two water-entry speeds. As a result, prediction and test results showed sufficient similarity to evaluate the identifiability of water-entry trace.

• The Korean Journal of Pain
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• v.26 no.3
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• pp.286-290
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• 2013

Air injected into the epidural space may spread along the nerves of the paravertebral space. Depending on the location of the air, neurologic complications such as multiradicular syndrome, lumbar root compression, and even paraplegia may occur. However, cases of motor weakness caused by air bubbles after caudal epidural injection are rare. A 44-year-old female patient received a caudal epidural injection after an air-acceptance test. Four hours later, she complained of motor weakness in the right lower extremity and numbness of the S1 dermatome. Magnetic resonance imaging showed no anomalies other than an air bubble measuring 13 mm in length and 0.337 ml in volume positioned near the right S1 root. Her symptoms completely regressed within 48 hours.

• Geotechnical Engineering
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• v.13 no.2
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• pp.39-54
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• 1997

Laboratory testings were carried out on plastic board drains (PBDs) using large scale test apparatus to evaluate the physical properties and the drainage performance. The test results reveal that the domestic products of PBDs are well compared with the foreign prod acts as far as the quality and drainage performance are concerned. It has also been confirmed that the discharge capacity decreases with time in such a way that the air bubbles are entrapped inside kinky PBDs and these air bubbles block the water flow through PBDs. It has been found that the vacuum pressure iseffectively applicable to recover the discharge capacity affected by the entrapped air bubbles.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.2
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• pp.217-224
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• 2017

This study proposes an evaluation method for time delay function(TDF) of Point Detonation(PD) fuse using underwater explosion and water entry phenomena. Until now, nothing but the naked eyes of an observer or video images have been used to determine whether the TDF of PD fuze is operated or not. The observer has verified the performance of TDF by analysing the shape of the plume formed by underwater explosion. However, it is very difficult to evaluate the TDF of PD fuse by these conventional methods. In order to overcome this issue, we propose a method using underwater sound signal emitted from the underwater explosion of high explosive charge. The result shows that the measured sound signal is in accord with the physical phenomena of water entry of warhead as well as underwater explosion. Also, from the hypothesis test of bubble period, difference on underwater sound analysis between dud event and delay one is proved.

• Progress in Superconductivity
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• v.6 no.2
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• pp.113-117
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• 2005

In this study, electromagnetic analysis of current paths including meander pattern, spiral pattern, and bi-spiral pattern were performed and in order to verity the analysis results, experiments tests including quench test, and insulation tests were performed. In addition, bubble corner concepts were introduced to enhance insulation reliability. From our study, bi-spiral pattern of YBCO thin films were rather effective for quench and insulation than the other patterns. So this current path pattern was adopted for YBCO thin films in order to develop 6.6 kV resistive fault current limiters. Finally YBCO thin films were connected in series and parallel to enhance capacity, and the test results of current limiting characteristics of 6.6kV resistive SFCL were successful. The Progress in Superconductivity is published every six month and serves as a channel for publications on superconductivity and related topics. The author(s) are required to submit THREE copies of the manuscripts along with original figures directly to the Editor.