• Journal of Korean Neurosurgical Society
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• 제41권2호
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• pp.82-87
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• 2007

Objective : Pontine hemorrhages usually result in a much higher morbidity and mortality than any other intracranial vascular lesion. The purpose of this study was to evaluate survival and the contributing factors for patients with pontine hemorrhage. Methods : Of the 41 patients who were admitted to our hospital with their first acute pontine hemorrhage from 1997 to 2005, 35 patients were included in this study. Medical records were reviewed to confirm the accuracy of diagnosis and collect demographic, clinical and radiological data. The patients were divided into two groups, survivors and deceased patients; then the survivors were divided again into a group of patient with good results and those with poor results. The location of the hematoma, maximum anteroposterior [AP] diameter, maximum transverse diameter, hematoma volume, ventricular extension, extension into the midbrain, hydrocephalus and initial Glasgow coma scale [GCS] were evaluated. Results : The two year survival rate was 58.5%. The survival of patients with pontine hemorrhage was affected by initial GCS score and transverse hematoma dimeter. Functional outcome of patients who survived was affected by initial GCS, maximum transverse diameter, maximum AP diameter and hematoma volume. Conclusion : The rate of survival after pontine hemorrhage is associated with the transverse diameter of the hematoma and more importantly the initial GCS. Long-term outcome of survivors is influenced by the initial GCS, transverse diameter, AP diameter and volume. Through the multivariate analysis, initial GCS is the only significant factor on survival. Strictly speaking, initial GCS is not modifiable. However, surgical reduction may be considered to amend theses decisive factors. Additional study for indication, timing and method of surgical management is needed.

• 소성∙가공
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• 제11권8호
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• pp.710-715
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• 2002

This paper describes the numerical determination of optimum blank diameter for sound material flow and high precise thread profile of a spindle screw through external thread rolling using two-three roll dies. Initial blank diameter affects the dimensional accuracy and surface finish qualities of a spindle screw in thread rolling process, therefore it is very important to determine the optimum blank diameter in thread rolling process. In order to determine the optimum blank diameter, this paper suggests the calculation method of initial bland diameter considering the real shape of tooth. The finite element code DEFORM is applied to analyze the metal flow of tooth, and these analytical results are verified by thread rolling experiment for spindle screw.

• 한국분무공학회지
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• 제20권4호
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• pp.261-267
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• 2015

The main purpose of this study is to provide the information of soot generation of toluene fuel droplet. To achieve this, this paper provides the experimental results on the different initial diameter of toluene droplet combustion characteristics conducted under equivalent ambient pressure ($P_{amb}$) and oxygen concentration ($O_2$) conditions. Visualization of single fuel droplet was performed with high resolution CCD camera and visualization system. At the same time, ambient pressure ($P_{amb}$) and oxygen concentration ($O_2$) were maintained by ambient condition control system. Soot volume fraction ($f_v$) was analyzed and compared on the basis of intensity ratio ($I/I_0$) of background image. The result of soot generation was almost the same regardless of initial droplet diameter since thermophoretic flux is not much changed under the same ambient conditions. Soot standoff ratio (SSR) of 2 mm diameter showed unstable variation characteristics due to the short available measuring time.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.133-137
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• 2002

This paper summarizes the results of a numerical study conducted to analyze the determination of optimum blank diameter on material flow and thread profile for Spindle Screw in external thread rolling. Initial blank diameter affect a quality of Spindle Screw in thread rolling process. Therefore, it is very important to determine the optimum blank diameter in thread rolling process. In order to determine the optimum blank diameter, this paper suggest the calculating method of initial blank diameter considering real shape of tooth. The finite element code DEFORM is applied to analyze the metal flow of tooth. then the analytical results are verified by experiment of thread rolling for Spindle Screw.

• 한국분무공학회지
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• 제15권1호
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• pp.8-16
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• 2010

This paper present the diesel spray characteristics at different injection system parameters in a HSDI diesel engine. The spray characteristics was calculated by the coupled simulation of fuel injection system model and three-dimensional KIVA-3V code with TAB spray model. The relevant injection parameters are accumulator volume, control chamber initial volume, control orifice diameter, needle valve diameter and nozzle chamber initial volume, etc. Parametric investigation with respect to twelve relevant injection parameters showed that there was a significant advantage in varying control chamber initial volume, control chamber orifice diameter, and nozzle chamber orifice diameter with respect to effect the SMD and fuel injection speed. Consequently, in order to design the fuel injection system for spray characteristics, it seems reasonable to suppose to be optimized the fuel injection system.

• 한국분무공학회지
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• 제18권2호
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• pp.94-99
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• 2013

The spherically-symmetric burning of an isolated droplet is a dynamic problem that involves the coupling of chemical reactions and multi-phase flow with phase change. For the improved understanding of these phenomena, this paper presents the numerical results on the n-heptane droplet combustion conducted at a 1 atm ambient pressure in three different initial droplet diameter ($d_0$). The main purpose of this study is to provide basic information of droplet burning, extinction and flame behavior of n-heptane and improve the ability of theoretical prediction of these phenomena. To achieve these, the numerical analysis was conducted in terms of normalized droplet diameter ($d/d_0$), flame diameter ($d_f$) and flame standoff ratio (FSR) under the assumptions that the droplet combustion can be described by both the quasi-steady behavior for the region between the droplet surface and the flame interface and the transient behavior for the region between the flame interface and ambient surrounding.

• 한국임상수의학회지
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• 제39권4호
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• pp.149-155
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• 2022

The aim of this study was to compare the mechanical properties of 0.6 and 0.8 mm cerclage wires with the 1.0 mm cerclage wire in the twist, single-loop, double-loop, double-wrap, and loop/twist knot methods. Six stainless steel cerclage wires of various diameters in different knot methods were tied round a customized jig mounted on a load testing machine. The initial tension, initial stiffness, and yield load were evaluated. The failure mode of each cerclage was observed. For each wire size, the double-loop, double-wrap, and loop/twist knots showed significantly greater initial stiffness, and yield load than those seen with twist and single-loop knots. The single-loop knot showed the least initial stiffness regardless of the diameter. As the cerclage wire diameter increased, the cerclage tended to show significantly greater initial stiffness, and yield load. Failure modes varied depending on the knot configurations. Single-loop knots of smaller-diameter wires less than 1 mm had similar or lower initial tension, initial stiffness, and yield load than a twist knot. Owing to the variance in mechanical properties, the clinical application of the knot type should depend on the diameter of the cerclage wire.

• 대한기계학회논문집B
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• 제29권1호
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• pp.55-62
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• 2005

Combustion Characteristics and quenching criteria of micro combustor in various condition was exploited experimentally. Two different gases were used, and various geometric matrixes were considered to figure out quenching characteristic of micro combustor. The micro combustor studied in this study was constant volume, and has cylindrical shape. Geometric parameter of combustor was defined to be combustor height and diameter. The effect of height was exploited parametrically as 1 mm, 2mm and 3mm and the effect of diameter was parameterized to be 7.5mm and 15mm. Three different combustibles. (1) Stoichiometric mixture of methane and are, (2) Stoichiometric mixture of hydrogen and air and (3) Mixture of hydrogen and air with fuel stoichiometry of two were used. Pressure transition during combustion process was recovered. The ratio of maximum pressure to initial pressure responded favorably with the change of height of combustor and the initial pressure, the maximum pressure was also increased. The flame propagation was observed only when a specific condition was satisfied. From the experiment the condition that guarantees stable propagation of flame was tabulated. The tabulated results includes criteria of quenching according to combustor height, combustor diameter, species of fuel and initial pressure.

• 대한의용생체공학회:의공학회지
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• 제24권2호
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• pp.113-119
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• 2003

본 연구에서는 end-to-end 문합시 변형된 직경의 불일치로 인하여 발생하게 되는 혈관질환을 방지하기 위하여 기계역학적 거동을 유한요소 법을 이용하여 해석한 결과를 나타내었다. 이 연구에서는 서로 다른 직경을 가지는 동맥과 인공혈관인 PTFE의 문합시 봉합으로 인한 예변형을 고려하였으며, 봉합된 문합부에 수축기혈압인 120mmHg(16.0KPa)을 작용시켜 혈관의 변형을 분석하였다. 변형 후 최종 문합부의 형상은 동맥과 PTFE의 초기 직경비(R$_{I}$)와 PTFE의 두께에 대하여 분석하였다. 그리고 동맥과 PTFE의 초기 직경비가 문합부에서 발생되는 응력에 어떠한 영향을 미치는지에 대하여 해석하여 다음과 같은 결과를 얻었다. 1. 혈관내막의 증식등을 고려하지 않고 봉합으로 인한 예변형과 수축기 혈압만을 고려할 경우 가장 이상적인 초기 직경비(R$_{I}$)는 1.073이다. 2. 상당응력과 원주방향응력은 초기 직경비(R$_{I}$) 증가에 따라 증가하며 모두 접합부에서 PTFE측으로 0.4mm 떨어진 지점에서 최대값이 발생하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.239-242
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• 2008

원통형 형상의 연료 그레인을 적용한 하이브리드 추진 시스템에서 연료포트 초기 직경에 따른 연소특성을 고찰하였다. 산화제에 따라 달라지는 연료포트 직경에 따른 연소특성 변화를 알아보고자 산화제로는 GOX와 $GN_2O$를 적용하였고, 고체연료로는 PE를 적용해 실험을 수행하였다. 동일 산화제 유량에서 산화제와 상관없이 고체연료의 초기 포트직경이 커짐에 따라 연소량이 감소함을 확인했고, 산화제로 $GN_2O$를 적용한 경우가 산화제로 GOX를 적용한 경우보다 연료포트 초기 직경에 따른 연소량 차이가 줄어듦을 확인하였다.