• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.549-554
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• 2013

For the past years, higher power rating 2 stroke super long stroke diesel engines having more than 8 cylinders and larger cylinder bore are installed mainly on very large containerships to save on fuel consumption. However, these engines are prone to X-mode vibration due to $2^{nd}$ node torsional vibration or the X-type moment, particularly because of the increase in total length and height. Recently, cases of excessive X-mode vibration often occurred on engine's major components. This vibration is manifested also as secondary vibration causing failure in engine-mount large structures. This study investigated the excitations caused by the $2^{nd}$ node propulsion shafting torsional vibration that influence X-mode vibration of the main engine and practical countermeasures are proposed. An 8RT-82RT-flex 8 cylinder engine and 11S90S-ME 11 cylinder engine for a container ship was used as research model.

• Journal of Chest Surgery
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• 제40권4호
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• pp.292-296
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• 2007

배경: 이 연구에서는 원발성 자연기흉 환자의 초 치료를 위해, 본 교실에서 2005년부터 사용하기 시작한 상품화된 8 Fr 흉부 배액 도관($Pleuracan^{(R)}$)의 효용성에 대해 알아보고자 하였다. 대상 및 방법: 2004년 7월부터 2006년 7월까지 원발성 자연기흉으로 진단받고 흉관 삽입술을 시행한 환자 59명(72 예)을 대상으로 하였으며, 20 Fr 이상의 흉관을 사용한 군(Tube군, T군)과 $Pleuracan^{(R)}$을 사용한 군($Pleuracan^{(R)}$군, P군)으로 나누어 그 임상 경과를 후향적으로 비교하였다. 결과: 총 41예에서 $Pleuracan^{(R)}$을 삽입하였으나, 9.8% (4/41)에서 도관 기능 장애가 나타났고, 이 중 3예에서는 20 Fr이상의 흉관을 삽입하였다. 따라서 최종적으로 T군은 34예, P군은 38예였다. 두 군 사이에 흉관 거치 기간(T군: $2.1{\pm}1.5$일, P군: $2.1{\pm}1.3$일), 재원 일수(T군: $6.4{\pm}5.4$일, P군: $5.2{\pm}2.9$일), 합병증(T군: 3% (1/34, 출혈), P군: 0%) 등에는 유의한 차이가 없었으나, 정주용 진통제 사용 환자는 P군이 60% (23/38)로 91%(31/34)인 T군에 비해 유의하게 적었다(p=0.003). 수술 얼이 흉관 삽입만으로 치료한 36예(T군: 17예, P군: 19예)만을 분석하였을 때도 동일한 결과를 얻었으며, 이 환자들에 있어 공기 누출 기간은 T군이 $0.5{\pm}0.7$일, p군이 $0.5{\pm}1.2$일로 차이가 없었고, P군의 84% (16/19)에서 폐의 재팽창을 얻어 94% (16/17)의 T군과 비교하여 유의한 차이가 없었다. 결론: $Pleuracan^{(R)}$은 20 Fr 이상의 흉관과 비교하여 그 효용성에 차이가 없어, 원발성 자연기흉의 초 치료에 사용될 수 있다고 생각한다.

• 한국자동차공학회논문집
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• 제15권5호
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• pp.9-16
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• 2007

Since the liquid phase LPG injection(LPLI) system has an advantage of higher power and lower emission characteristics than the mixer type fuel supply system, many studies and applications have been conducted. However, the heat extraction, due to the evaporation of liquid fuel, causes not only a dropping of LPG fuel but also icing phenomenon that is a frost of moisture in the air around the nozzle tip. Because both lead to a difficulty in the control of accurate air fuel ratio, it can result in poor engine performance and a large amount of HC emissions. The experimental investigation was carried out on the bench test rig in this study. It was found that n-butane, that has a relatively high boiling point($-0.5^{\circ}C$), was a main species of droplet composition and also found that the droplet problem was improved by the use of a large inner to outer bore ratio nozzle whose surface roughness is smooth. The icing phenomena were decreased when the an engine head temperature was increased, although a large amount of icing deposit was still observed in the case of $87^{\circ}C$. Also, it was observed that the icing phenomenon is improved by using anti-icing bushing.

• Journal of Chest Surgery
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• 제36권1호
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• pp.51-54
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• 2003

환자는 53세 남자로 식도 정맥류 파열로 Sengstaken-Blaceore관을 삽관하였다. Sengstaken-Blaccore관 삽관 이틀 후 좌측에 혈흉이 생겨 본원으로 전원되었다. 식도내시경 소견상 길이 8cm에 이르는 거대 흉부 식도 파열이 관찰되었다. 반복되는 식도 정맥류 출혈과 전신 상태의 악화 등으로 좌측 개흉술을 식도 파열 후 33 일째에 실시하였다 좌측 농흉과 8cm크기의 위아래로 파열된 식도를 관찰할 수 있었다. 파열부위는 변연절제 후 단순 봉합하고, 파열된 식도 부위의 위 아래 경계부위에서 각각 2cm 거리를 두고 비흡수성 스테플러(TA stapler 60 H 4.8)를 이용하여 배제시킨 뒤 흉관을 위치시켰다. 흉부 식도 배제술 6일 후 실시한 식도 조영술에서 위쪽 스테플링한 부위와 연하여 누출이 관찰되었다. 경부식도 배제술을 같은 방법으로 실시하였다. 환자는 파열된 흉부 식도 배제술 137일 후, 이차적인 식도 재건술없이 경구로 음식의 섭취가 가능하였다.

• Interaction and multiscale mechanics
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• 제4권4호
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• pp.291-311
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• 2011

To simulate the self excited torsional vibrations of rotating drill strings (DSs) in vertical bore-holes, the nonlinear wave models of homogeneous and sectional torsional pendulums are formulated. The stated problem is shown to be of singularly perturbed type because the coefficient appearing before the second derivative of the constitutive nonlinear differential equation is small. The diapasons ${\omega}_b\leq{\omega}\leq{\omega}_l$ of angular velocity ${\omega}$ of the DS rotation are found, where the torsional auto-oscillations (of limit cycles) of the DS bit are generated. The variation of the limit cycle states, i.e. birth (${\omega}={\omega}_b$), evolution (${\omega}_b<{\omega}<{\omega}_l$) and loss (${\omega}={\omega}_l$), with the increase in angular velocity ${\omega}$ is analyzed. It is observed that firstly, at birth state of bifurcation of the limit cycle, the auto-oscillation generated proceeds in the regime of fast and slow motions (multiscale motion) with very small amplitude and it has a relaxation mode with nearly discontinuous angular velocities of elastic twisting. The vibration amplitude increases as ${\omega}$ increases, and then it decreases as ${\omega}$ approaches ${\omega}_l$. Sectional drill strings are also considered, and the conditions of the solution at the point of the upper and lower section joints are deduced. Besides, the peculiarities of the auto-oscillations of the sectional DSs are discussed.

• 한국자동차공학회논문집
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• 제3권1호
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• pp.54-64
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• 1995

The effects of swirl on early flame development and late combustion characteristic were investigated using a high speed single-shot visualized 51 engine. LDV measurements were performed to get better understanding of the flow field in this combustion chamber. Spark plugs were located at half radius (R/2) and central location of bore. High speed schlieren photographs at 20,000 frames/sec were taken to visualize the detailed formation and development of the flame kernel with cylinder pressure measurements. This study showed that high swirl gave favorable effects on combustion-related performances in terms of the maximum cylinder pressure and flame growth rate regardless of spark position. However, at R/2 ignition the low swirl shown desirable effects at low engine speed gave worse performances as engine speed increased than without swirl. There were distinct signs of slow-down in flame growth during the period when the flame front expanded from 2.5mm in radius until it reached 5.0mm apparently due to the presence of ground electrode. There seemed to be heat transfer effect on the flame expansion speed which was evidenced in high swirl case by the slowdown of the late flame front presumably caused by relatively large heat loss from burned gas to wall compared with low- or no-swirl cases.

• ALGAE
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• 제31권4호
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• pp.289-301
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• 2016

Floating debris provides substrates for dispersal of organisms by ocean currents, including algae that thrive on plastics. The 2011 earthquake and tsunami in Tohuku, Japan resulted in large amounts of debris carried by the North Pacific Current to North America from 2012 to 2016. In 2015-2016, the plastics in the debris bore a complex biota including pink algal crusts. One sample (JAW4874) was isolated into culture and a three-gene phylogeny (psbA, rbcL, and SSU) indicated it was an unknown member of the red algal class Stylonematophyceae. It is a small pulvinate crust of radiating, branched, uniseriate filaments with cells containing a single centrally suspended nucleus and a single purple to pink, multi-lobed, parietal plastid lacking a pyrenoid. Cells can be released as spores that attach and germinate to form straight filaments by transverse apical cell divisions, and subsequent longitudinal and oblique intercalary divisions produce masses of lateral branches. This alga is named Tsunamia transpacifica gen. nov. et sp. nov. Sequencing of additional samples of red algal crusts on plastics revealed another undescribed Stylonematophycean species, suggesting that these algae may be frequent on drift oceanic plastics.

• Journal of Yeungnam Medical Science
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• 제31권1호
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• pp.17-20
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• 2014

Iatrogenic femoral artery pseudoaneurysm is a complication in patients undergoing catheterization. The risk increased when large-bore sheaths, concomitant anticoagulation therapy, and antiplatelet therapy are used during the intervention. Ultrasound-guided thrombin injection has become the treatment of choice. Rapid expansion, rupture, infection, and mass effect resulting in distal or cutaneous ischaemia or peripheral neuropathy, as well as failure of other treatment options are all indications for surgery. We report a 48-year-old man who developed hemorrhagic shock due to femoral pseudoaneurysm rupture after coronary angiography, and successfully treated by ultrasound-guided thrombin injection.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1285-1289
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• 2006

In a large diameter piping system, high frequency energy can produce excessive noise, high vibration, and failures of thermo-well, instrumentation, and attached small-bore piping. High frequency energy is generated by flow induced vibration like vortex shedding in orifices and valves. Once this energy is generated, amplification may occur from acoustical and/or structural resonances, resulting in high amplitude vibration and noise. At low frequencies, pipe vibration occurs laterally along the pipe's length, but at higher frequencies, the pipe shell wall vibrates radially across its cross-section. The simple beam analogy which is based on the beam mode vibration can not be applied to evaluate shell mode vibration. ASME OM3 recommends that the stress be measured directly by strain gauge and be evaluated according to the fatigue curves of the piping material. This Paper discusses the excitation and amplification mechanism relevant to high frequency energy generation in piping system, the monitoring method of the shell mode vibration in ASME OM3, the evaluation method generally used in the industry. Finally this paper presents the stress evaluation of the cavitating venturi down stream piping, where high frequency shell mode vibrations were observed during the operation.

• Journal of Magnetics
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• 제14권2호
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• pp.75-79
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• 2009

Nickel (Ni) and ferrite ($Fe_3O_4$, $NiFe_2O_4$) nanoparticles were synthesized by LGC using both wire feeding (WF) and micron powder feeding (MPF) systems. Phase evolution and magnetic properties were then investigated. The Ni nanopowder included magnetic-ordered phases. The LGC synthesis yielded spherical particles with large coercivity while the abnormal initial magnetization curve for Ni indicated a non-collinear magnetic structure between the core and surface layer of the particles. Since the XRD pattern cannot actually distinguish between magnetite ($Fe_3O_4$) and maghemite (${\gamma}-Fe_2O_3$) as they have a spinel type structure, the phase of the iron oxide in the samples was unveiled by $M{\ddot{o}}ssbauer$ spectroscopy. The synthesized Ni-ferrite consisted of single domain particles, including an unusual ionic state. The synthesized nanopowder bore an active surface due to the defects that affected abnormal magnetic properties.