• 한국연소학회지
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• 제3권1호
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• pp.59-69
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• 1998

The results of study on the active control of naturally occurring combustion oscillations with a single dominant frequency in an atmospheric dump combustor are presented. Control was achieved by an oscillatory infection of secondary fuel at the dump plane. A high speed solenoid valve with a maximum frequency of 250Hz was used as the actuator and a sound level meter, located at the combustor exit, measured the pressure fluctuations which served as the feedback signal for the control loop. Instability characteristics were mapped over a range of mean mixing section velocities from 6.7 m/s-9.3 m/s and with three mixing conditions. Different fuel/air mixing conditions were investigated by introducing varying percentages of primary fuel at two locations, one at the entrance to the mixing section and one 6 mixing tube diameters upstream of the dump plane. Control studies were conducted at a mean velocity of 9.3 m/s, with an air temperature of $415^{\circ}C$, and from flame blowout to the stoichiometric condition.

• Journal of Korean Neurosurgical Society
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• 제42권5호
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• pp.406-409
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• 2007

Craniovertebral junction (CVJ) tuberculosis is a rare disease, potentially causing severe instability and neurological deficits. The authors present a case of CVJ tuberculosis with atlantoaxial dislocation and retropharyngeal abscess in a 28-year-old man with neck pain and quadriparesis. Radiological evaluations showed a widespread extradural lesion around the clivus, C1, and C2. Two stage operations with transoral decompression and posterior occipitocervical fusion were performed. The pathological findings confirmed the diagnosis of tuberculosis. Treatment options in CVJ tuberculosis are controversial without well-defined guidelines. But radical operation (anterior decompression and posterior fusion and fixation) is necessary in patient with neurological deficit due to cord compression, extensive bone destruction, and instability or dislocation. The diagnosis and treatment options are discussed.

• 대기
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• 제27권2호
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• pp.177-188
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• 2017

The development mechanisms of an unusual heavy snowfall event, which occurred in the coast of Jeju Island on 23 January 2016 were investigated through a thermodynamic approach. The formation of heavy snowfall was attributed to the enhanced thermal convection in two ways. First, the convection was enhanced by the air-sea temperature difference between the cold air advection in low-troposphere associated with the strengthening of the Siberian High and abnormal warm sea surface temperature, which is $1{\sim}2^{\circ}C$ higher than normal year over the Yellow Sea (YS). Second, the convective instability was increased by the vertical temperature gradient between the 7 days-sustained cold air advection in low-troposphere and the abrupt cold air intrusion in mid-troposphere induced by the southward shift of a cold cut-off vortex ($-45^{\circ}C$) at the formation stage. Compared to the twelve hours prior to the formation, the low-level moisture increased by 5% through the moisture supply from the YS, and the air-sea temperature difference increased from $18.5^{\circ}C$ to $28.5^{\circ}C$. Furthermore, the upward sensible (latent) heat flux increased 1.5 (1.2) times over the YS before the twelve hours prior to the formation. Thereafter, the sustained moisture supply and upward turbulent heat flux helped to maintain the snowstorm.

• 대한화학회지
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• 제35권5호
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• pp.480-486
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• 1991

아닐린 및 o-클로로아닐린 용액내에서 브롬화에탄의 용해도를 5, 1.5$^{\circ}$ 및 25$^{\circ}$C에서 브롬화칼륨이 존재할 때와 존재하지 않을 때의 두 경우에 대하여 각각 측정하여 보았다. 브롬화칼륨이 존재하지 않을 때에 o-클로로아닐린에서 브롬화에탄의 용해도가 아닐린에서 보다 크다. 이것은 브롬화에탄과 o-클로로아닐린의 상호작용이 아닐린보다 더 강하다는 것을 나타낸다. 그리고 브롬화칼륨이 존재할 경우에는 용액내에서 브롬화에탄과 브롬화칼륨이 불안정한 착물이 생성된다. 이 착물을 여러 경우로 가정하여 계산하여 본 결과 1:1 착물일 때, 불안정 상수 K값이 비교적 일정한 값을 나타내었다. 그러므로 1:1 착물 $C_2H_5Br[\cdot}GaBr_3$가 형성됨을 알았으며, 이 착물은 용액내에서 다음 평형식에 의해서 이루어진다고 본다. $C_2H_5Br{\cdot}GaBr_3\;{\rightleftharpoons}\;C_2H_5Br+1/2Ga_2Br_6$ 브롬화칼륨과 브롬화에탄의 착물의 불안정도를 이와 대응하는 브롬화메탄과 비교하여 보았다. 또한 이 착물의 해리에 대한 엔탈피, 자유에너지 및 엔트로피 변화도 산출하였다.

• Nuclear Engineering and Technology
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• 제19권3호
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• pp.169-179
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• 1987

소형시험편(1/2"T)을 이용, 균열진전량 및 J계산식에 따른 재료의 J-R (J-T) 곡선의 변화를 조사하여 신뢰성있는 J-R(J-T) 곡선을 구하기 위한 실험 및 해석방법을 고찰하였다. 시험은 국내 원자력발전소 압력용기감시 시험에 포함되어 있는 파괴인성시편과 꼭같이 SA 533 Grade 3, Class1 재료로 제작한 1/2"T, C-T 시편을 이용, Single Specimen Unloading Compliance Technique으로 수행하였다. 시험 및 해석결과 Ernst의 Deformation theory J (JD)식을 이용하여 초기 Uncracked ligament (be)의 25～30%까지 균열을 진전시켜 구한 J-R(J-T) 곡선이 대형시편의 결과와 가장 유사한 값을 나타내었다. 한편 Ernst의 Modified J (JM)식에 의한 J-R (J-T) 곡선은 Deformation theory J(JD)에 의한 J-R(J-T) 곡선보다 다소 높은 Instability 예측점을 얻을 수 있기 때문에 실제 압력용기 안전성 해석시에는 가동률향상 및 수명연장 측면에서 Modified J의 사용은 고려되어야 할 것이다.되어야 할 것이다.

• 소성∙가공
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• 제15권4호
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• pp.333-339
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• 2006

Hot deformation behavior of a carbon steel (A350 LF2) was characterized by compression tests in the temperature range of $800-1250^{\circ}C$ and the strain rate range of $0.001-10s^{-1}$, The microstructural evolution during hot compression was investigated and deformation mechanisms were analyzed by constructing a deformation processing map. Processing maps were generated using the combination of dynamic material model (DMM) and flow instability theories based on the flow stability criteria and Ziegler's instability criterion. In order to evaluate the reliability of the map, the mirostructural characteristics of the hot compressed specimens were correlated with test conditions in the stable and unstable regime. The combined microstructural and processing map of A350 LF2 was applied to predict an optimum condition and unstable regions for hot forming.

• 기계저널
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• 제16권2호
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• pp.84-91
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• 1976

An experimental investigation of the natural circulating boiling flow characteristic in three cases of annulus with different outer diameter, and the effect of annular gap size on the burnout behavior is presented. The experimental work was conducted for each case of test section at system pressure of $1kg/cm^2$ and inlet subcooling $0-20^{\circ}C$ in the full range of throttling ratio. As the result, the following facts were found. 1) With the increase of ${\Delta}T_{sub}$, $D_{2}$ and A/A_{o}$, $q_{BO}$ increases on the whole, and with the decrease of ${\Delta}T_{sub}$ and $D_{2}$, hydrodynamic instability is accelerated to happen prematually. 2)With the increase of ${\Delta}T_{sub}$, $D_{2}$ and A/A_{o}$ burnout characteristic shows the high velocitylow quality burnout, and with the decrease, low-velocity-high quality burnout. 3)With the decrease of A/A_{o}$, hyddrodynamic instability is singnificantly restrained and the difference of $q_{BO}$ in each $D_2$ under same condition is gradually reduced, finally converging into $1.9{\times}10^{5}kcal/m^{2}-hr$.

• 대한화학회지
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• 제35권4호
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• pp.301-307
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• 1991

니트로벤젠 및 m-크실렌 용액내에서 1-요오드화프로판의 용해도를 8$^{\circ}$, 15$^{\circ}$및 25$^{\circ}C$에서 요오드화칼륨이 존재할 때와 존재하지 않을 때의 두 경우에 대하여 각각 측정하여 보았다. 요오드화칼륨이 존재하지 않을 때에 m-크실렌에서 1-요오드화프로판의 용해도가 니트로벤젠에서 보다 크다. 이것은 1-요오드화프로판과 m-크실렌의 상호작용이 니트로벤젠보다 더 강하다는 것을 나타낸다. 그리고 요오드화칼륨이 존재할 경우에는 용액내에서 1-요오드화프로판과 요오드화칼륨이 불안정한 착물이 생성된다. 이 착물을 여러 경우로 가정하여 계산하여 본 결과 1:1 착물일 때, 불안정 상수 K값이 비교적 일정한 값을 나타내었다. 그러므로 1:1 착물 n-C$_3H_7I{\cdot}GaI_3$가 형성됨을 알았으며, 이 착물은 용액내에서 다음 평형식에 의해서 이루어 진다고 본다. n-C$_3H_7I{\cdot}GaI_3{\rightleftharpoons}n-C_3H_7I+1/2Ga_2I_6$ 요오드화칼륨과 1-요오드화프로판의 착물의 불안정도를 이와 대응하는 요오드화메틸과 비교하여 보았다. 또한 이 착물의 해리에 대한 엔탈피, 자유에너지 및 엔트로피 변화도 산출하였다.

• Journal of Microbiology
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• 제34권2호
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• pp.166-171
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• 1996

Genetic analysis was conducted on newly isolated coliphages form soil by using a RAPD assay. From the initial result, the coliphages were turned out to be different form one another but were closely related to .psi..lambda. due to the fact that they shared the samed RAPD maker in which other T phage testings failed to show. By using the primers EC01 or EC02, a fast genetic mutation of .psi.C1 was found by producing specific RAPD markers on the phages from the first filial progeny to the second filial progeny. When we made a RAPD assay with combined primers (EC01, EC05 and EC08), the genetic mutation was again confirmed in .psi.C1. The assay detection showed mutations in other coliphages such as .psi.C2 and .psi.C3 by revealing specific RAPD bands among different progeny phages, where genetic instability of the coliphages in implied.

• Journal of Korean Neurosurgical Society
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• 제58권1호
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• pp.89-92
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• 2015

Rheumatoid arthritis (RA) is a chronic inflammatory disease involving multiple joints. The cervical spine is often affected, and cases involving atlantoaxial joint can lead to instability. Anterior atlantoaxial subluxation in RA patients can lead to posterior neck pain or occipital headache because of compression of the C2 ganglion or nerve. Here, we report the successful treatment of a RA patient with occipital radiating headache using pulsed radiofrequency therapy at the C2 dorsal root ganglion.