• 공업화학
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• 제10권4호
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• pp.531-536
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• 1999

누출시험 장치를 이용하여 미량 물 누출 실험을 수행하였다. 2.25Cr-1Mo 시편의 누출경로는 나트륨-물 반응 생성물에 의해 plugging되는 경우가 발생하였으나, 대부분 re-open상태를 나타내었다. 또한 누출 경로가 완전 re-open된 후 나트륨 부위에서 시편의 self-wastage pattern은 온도에 영향을 받지 않음을 알 수 있었으며, 누출경로가 re-open 되면서 나타나는 defected 크기는 대략 5 mm 이내임을 알 수 있었다. 누출 경로가 완전 re-open 되는데 걸리는 시간은나트륨 온도가 높을수록 짧게 나타났으며, 평균적으로 $450^{\circ}C$에서 143분, $475^{\circ}C$의 경우 40.7분, $510^{\circ}C$의 경우 34.7분을 나타내었다.

• 터널과지하공간
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• 제6권3호
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• pp.209-222
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• 1996

Shut-in pressure, reopenting pressure and fracture orientation are very important parameters to be evaluated precisely in in-situ stress measurement by hydraulic fracturing. Graphical methods on pressure-time curves have been conventionally used, even though these are seriously dependent on subjectivity of interpreters. So there have been many demands on new method to objectivity in determining parameters. We have developed integrated hydrofracturing data processing program (HYDFRAC), based on nonlinear regression analysis and can be invoked under the Window graphical user interface. HYDFRAC consiste of three routines, that is shut-in pressure routine, reopening pressure routine, and fracture delineation routine. Each of routines include independent modules according to parameter determination methods. Its application to field tests ensured both objectivity and facility in determining of hydraulic fracturing parameters. Determining shut-in pressures at each pressurization cycles, we adopted the exponential pressure-decay method(EPD method), the bilinear pressure-decay-rate method (PDR method), and the tangent intersection method in order to find the pressurization-cyclic tendency of shut-in pressures. The estimated pressure by PDR method exists in the range of the upper and lower values by EPD method, and lies near to the upper value more than the lower. Being the pressurization cycle increased, the range of upper and lower limits come to be stabilized gradually. By graphical superposition method and bilinear pressure-accumulated volume method, reopening pressures were determined. Vertical and inclined fracture attitudes were determined by applying the directional statistics and sinusoidal curve fitting, respectively. The results of evaluation of hydrofracturing parameters showed that statistical methods could enhance the objectivity better than graphical methods.

• Journal of Chest Surgery
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• 제28권11호
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• pp.977-982
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• 1995

Early repair of complex congenital heart malformation may lead to life-threatening respiratory and hemodynamic embarrassment on sternal closure. We performed delayed sternal closure in nine neonates to avoid a fatal outcome in these situations. Primary elective open sternum was used in 8 [66.7% and primary sternal closure in 4 [33.3% of the 12 patients studied. one patient with primary sternal closure underwent delayed sternal reopening in the intensive care unit. Of the 9 patients with open sternum, 2 patients died of low cardiac output and acute renal failure respectively before delayed sternal closure. 7 patients could undergo delayed sternal closures 3 days after initial operation. The mean age at open cardiac procedure was 14.3 days [range 3 to 30 and mean preoperative weight was 3.4kg [range 2.8 to 4.1 . The aortic cross-clamping time was longer in the group with open sternum than the group with closed sternum [p=0.042 . There was no morbidity and mortality related to delayed sternal closure. Given the low morbidity and potential benifits, this technique should be used in neonates after open heart procedures when postoperative mediastinal compression produces frank low cardiac output or respiratoy compromise during a trial of sternal closure.

• Journal of Korean Neurosurgical Society
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• 제51권2호
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• pp.75-80
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• 2012

Objective : To optimize the recanalization of acute cerebral stroke that were not effectively resolved by conventional intraarterial thrombolysis (IAT), we designed a double device technique to allow for rapid and effective reopening. In this article, we describe the feasibility and efficacy of this technique. Methods : From January 2008 to September 2009, twenty patients with acute cerebral arterial occlusion (middle cerebral artery : n=12; internal carotid artery terminus : n=5; basilar artery : n=3) were treated by the double device technique. This technique was applied when conventional thrombolytic methods using drug, microwires, microcatheters and balloons did not result in recanalization. In the double device technique, two devices are simultaneously placed at the lesion (for example, one microcatheter and one balloon or two microcatheters). Chemicomechanical or mechanicomechanical thrombolysis was performed simultaneously using various combinations of two devices. Recanalization rates, procedural time, complications, and clinical outcomes were analyzed. Results : The initial median National Institute of Health Stroke Scale (NIHSS) was 16 (range 5-26). The double device technique was applied after conventional IAT methods failed. Recanalization was achieved in 18 patients (90%). Among them, 55% (11 cases) were complete (thrombolysis in cerebral infarction 2B, 3). The median thrombolytic procedural time including the conventional technique was $135{\pm}83.7$ minutes (range 75-427). Major symptomatic hemorrhages (neurological deterioration ${\geq}4$ points in NIHSS) developed in two patients (10%). Good long term outcomes (modified Rankin Scale ${\leq}2$ at 90 days) occurred in 25% (n=5) of the cases. Mortality within 90 days developed in two cases (10%). Conclusion : The double device technique is a feasible and effective technical option for large vessel occlusion refractory to conventional thrombolysis.

• 암석학회지
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• 제26권4호
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• pp.341-352
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• 2017

영덕 서부에서 산출되는 지품화산암층은 하부로부터 유문암질 화성쇄설암, 층회암, 안산암질 유리쇄설암, 유문암 용암, 응회질 역암, 안산암 용암 순으로 구성되는 층서단위이다. 유문암질 화성쇄설암은 SHRIMP U-Pb 연대측정에 의해 $68.5{\pm}1.6Ma$로 측정되었다. 이 층서단위는 이 무렵에 대부분 유문암질 화산작용에 의해 형성되었으며 국부적이지만 다른 화구로부터 안산암질 화산작용에 의해 추가되었다. 유문암질 화산작용은 먼저 수증기마그마성 폭발작용으로 인해 화성쇄설층을 형성시켰고, 나중에 유문암질 화산작용이 재개되어 기존 화구로부터 용암 분류작용으로 유문암질 용암돔을 형성하였다. 1차 및 2차 유문암질 화산작용 사이에 화산 말단부의 낮은 저지는 침수되어 층회암층이 퇴적되었고 연이어 다른 화구에서 안산암질 화산작용이 일어나 흘러나온 용암이 호수물과의 접촉에 의해 급냉파쇄작용으로 유리쇄설암을 형성하였으며, 마지막으로 다시 안산암질 용암이 재차 흘러들어와 지품화산을 얇은 안산암 용암층으로 덮었다.

• 만화애니메이션 연구
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• 통권17호
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• pp.175-186
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• 2009

한국만화영상진흥원은 2009년 새롭게 개관하면서 한국만화산업진흥과 한국만화문화진흥의 두 축을 <비즈니스센터>와 <뮤지엄 만화규장각>이라는 사업영역의 두 축으로 구분하는 동시에 두 건물로 분리했다. 사업의 성격상 당분간은 비즈니스센터에서 사업운영수익을 올리기는 쉽지 않으므로, 뮤지엄 만화규장각의 역할이 그만큼 중요하다. 전시, 도서열람 및 연구, 다양한 문화행위를 포괄하고 있다는 측면에서 멀티만화문화공간이라고 규정할 수 있는 이 공간의 운영계획을 세우는 것은 진흥원 전체에 있어서 필수불가결한 일이다. 본 논문에서 비록 세부적인 부분들까지 모두 언급할 수는 없다손 치더라도, 가장 주요한 요소라고 볼 수 있는 설립취지와 목적에 따른 조직과 인력구성에 대한 문제를 먼저 제기하고 차례로 운영수익의 문제-사업운영수익 및 재원확보-에 대해 접근하려고 한다.

• Advances in biomechanics and applications
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• 제1권2호
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• pp.127-141
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• 2014

A preliminary study of a new pulsatile pump that will work to a frequency greater than 1 Hz, is presented. The fluid-structure interaction between a Newtonian blood flow and a piston drive that moves with periodic speed is simulated. The mechanism is of double effect and has four valves, two at the input flow and two at the output flow; the valves are simulated with specified velocity of closing and reopening. The simulation is made with finite elements software named COMSOL Multiphysics 3.3 to resolve the flow in a preliminary planar configuration. The geometry is 2D to determine areas of high speeds and high shear stresses that can cause hemolysis and platelet aggregation. The opening and closing valves are modelled by solid structure interacting with flow, the rhythmic opening and closing are synchronized with the piston harmonic movement. The boundary conditions at the input and output areas are only normal traction with reference pressure. On the other hand, the fluid structure interactions are manifested due to the non-slip boundary conditions over the piston moving surfaces, moving valve contours and fix pump walls. The non-physiologic frequency pulsatile pump, from the viewpoint of fluid flow analysis, is predicted feasible and with characteristic of low hemolysis and low thrombogenesis, because the stress tension and resident time are smaller than the limit and the vortices are destroyed for the periodic flow.

• Advances in pediatric surgery
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• 제17권2호
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• pp.133-138
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• 2011

Extracorporeal membrane oxygenation (ECMO) has been utilized in congenital diaphragmatic hernia (CDH) patients with severe respiratory failure unresponsive to conventional medical treatment. We retrospectively reviewed 12 CDH patients who were treated using ECMO in our center between April 2008 and February 2011. The pre ECMO and on ECMO variables analyzed included gestational age, sex, birth weight, age at the time of ECMO cannulation, arterial blood gas analysis results, CDH location, timing of CDH repair operation, complications and survival. There were 9 boys and 3 girls. All patients were prenatally diagnosed. Mean gestational age was $38.8{\pm}1.7$ weeks and mean birth weight was $3031{\pm}499$ gram. Mean age at the time of ECMO cannulation was $29.9{\pm}28.9$ hours. There were 4 patients who survived. Survivors showed higher 5 min Apgar scores ($8.25{\pm}0.96$ vs. $7.00{\pm}1.20$, p=0.109), higher pre ECMO mean pH ($7.258 {\pm}0.830$ vs. $7.159{\pm}0.986$, p=0.073) and lower pre ECMO $PaCO_2$ ($48.2{\pm}7.9$ vs. $64.8{\pm}16.1$, p=0.109) without statistical significance. The hernia was located on the left side in 10 patients and the right side in 2 patients. The time interval from ECMO placement to operative repair was about 3~4 days in 5 early cases and around 24 in the remaining cases. There were 3 cases of post operative bleeding requiring re operation and 2 cases of abdominal compartment syndrome requiring abdominal fascia reopening. ECMO catheter reposition was required in 4 cases. Three cases of arterial or venous thrombosis were detected and improved with follow up. Our data suggests that ECMO therapy could save the lives of some neonates with CDH who can not be maintained on other treatment modalities. Protocolized management and accumulation of case experience might be valuable in improving outcomes for neonates with CDH treated with ECMO.

• 한국구조물진단유지관리공학회 논문집
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• 제23권3호
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• pp.103-110
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• 2019

다양한 원인에 의한 포장체에 손상이 발생하면 신속한 통행재개를 위한 급속보수가 필요하게 된다. 산화마그네슘인산염복합체의는 경화시간이 짧고, 조기 강도발현이 가능하여 급속보수재료로 적합한 특성을 갖고 있다. 연구에서는 경소마그네시아와 제1인산칼륨을 결합하여 보수재료로 개발하기 위하여 물-결합재(W/B)비, 마그네슘-인산염(M/P)비 등의 배합비를 조정하면서 경화와 강도특성을 평가하고자 하였다. 그리고 현장 적용시의 작업성을 확보하기 위하여 표준사와 일반모래에 따른 거동차이와 지연제별 특성을 평가하였다. 실험결과 물-결합재비는 35%내외와 마그네슘-인산염비는 1.0~1.2 내외가 강도측면에서 가장 적합한 것으로 분석되었다. W/B비 0.35, M/P비 1.2 변수에서 1일 강도 25.0MPa 이상 발현되어 조기 보수재료로서 활용가능성이 충분한 것으로 분석되었다. 작업시간 확보를 위해서는 붕산을 지연제로 사용하는 것이 적합한 것으로 나타났으며, 산화마그네슘의 순도는 90~95%내외가 경화시간 확보를 위해 효과적인 것으로 나타났다.

• Journal of Cerebrovascular and Endovascular Neurosurgery
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• 제26권1호
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• pp.1-10
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• 2024

Objective: Endovascular coil embolization is the primary treatment modality for intracranial aneurysms. However, its long-term durability remains of concern, with a considerable proportion of cases requiring aneurysm reopening and retreatment. Therefore, establishing optimal follow-up imaging protocols is necessary to ensure a durable occlusion. This study aimed to develop guidelines for follow-up imaging strategies after endovascular treatment of intracranial aneurysms. Methods: A committee comprising members of the Korean Neuroendovascular Society and other relevant societies was formed. A literature review and analyses of the major published guidelines were conducted to gather evidence. A panel of 40 experts convened to achieve a consensus on the recommendations using the modified Delphi method. Results: The panel members reached the following consensus: 1. Schedule the initial follow-up imaging within 3-6 months of treatment. 2. Noninvasive imaging modalities, such as three-dimensional time-of-flight magnetic resonance angiography (MRA) or contrast-enhanced MRA, are alternatives to digital subtraction angiography (DSA) during the first follow-up. 3. Schedule mid-term follow-up imaging at 1, 2, 4, and 6 years after the initial treatment. 4. If noninvasive imaging reveals unstable changes in the treated aneurysms, DSA should be considered. 5. Consider late-term follow-up imaging every 3-5 years for lifelong monitoring of patients with unstable changes or at high risk of recurrence. Conclusions: The guidelines aim to provide physicians with the information to make informed decisions and provide patients with high-quality care. However, owing to a lack of specific recommendations and scientific data, these guidelines are based on expert consensus and should be considered in conjunction with individual patient characteristics and circumstances.