• 한국정밀공학회지
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• 제14권9호
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• pp.80-89
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• 1997

Die sinking electrical discharge machining(EDM) was conducted for ceramic composite of 33 weight percent TiC based on AI$_{2}$O$_{3}$ ceramic matrix according to the change of current and duty factor(DF). Material removal rate(MRR) was increased as the current and the duty factor increased, but better surface mor-pholoty was obtained in the region of lower current and duty factor. From the scanning electron microscopy(SEM) photographs and the energy dispersive X-ray spectroscopy(EDX) of the EDMed surface, EDM trace formed by one discharge spark was analyzed. Although the bending strength after EDM was highly decreased, reliability obtained by weibull analysis was increased twice. The bending strength was recovered or more by barrel polishing after EDM. From the FEM analysis of temperature for one spark, the possible melting region of AI$_{2}$O$_{3}$and TiC was obtained.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 제35회 춘계학술대회
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• pp.285-290
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• 2002

Screw in injection molding machine is affected by heat flux, pressure on inside barrel, geometry of screw including flight number, pitch and flight angle. Volumetric efficiency increases as the flight number increases, but it didn't show steady tendency according to helix angle of flight. Heat flux from heating pad and injection pressure play a very important role on the thermal behavior characteristics. The increased number of multi-flight is merits and demerits for a screw efficiency. So, we have to optimize flight number of the screw considering temperature, displacement, distortion and stress of the screw.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.143-146
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• 1991

This paper describes the analysis of a capacitor-driven induction coil-gun employing an equivalent circuit. The system differerntial equations are solved by using Runge-Kutta method. The velocity characteristics of projectile and current building in barrel ciols are studied. From the results, it is shown the optimal capacitance of capacitors, charging voltage and initial position of the projectile can be determined. These results will be used as the basis data for the design of capacitor driven coil-guns.

• Journal of Korean Neurosurgical Society
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• 제55권2호
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• pp.99-102
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• 2014

A previously healthy 52-year-old man presented to the emergency room with acute onset left hemiparesis and dysarthria. Brain computed tomography and magnetic resonance examinations revealed acute cerebral infarction in the right middle cerebral artery territory and a sphenoid ridge meningioma encasing the right carotid artery terminus. Cerebral angiography demonstrated complete occlusion of the right proximal M1 portion. A computed tomography perfusion study showed a wide area of perfusion-diffusion mismatch. Over the ensuing 48 hours, left sided weakness deteriorated despite medical treatment. Emergency extracranial-intracranial bypass was performed using a double-barrel technique, leaving the tumor as it was, and subsequently his neurological function was improved dramatically. We present a rare case of sphenoid ridge meningioma causing acute cerebral infarction as a result of middle cerebral artery compression.

• 한국군사과학기술학회지
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• 제5권4호
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• pp.9-18
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• 2002

In this paper, we have studied the characteristics of a perforated muzzle brake. The main purpose of a muzzle brake is to reduce the momentum being applied to the recoil system. Muzzle brake redirect a portion of the exiting gases to the side exerting a forward force on the brake, thus reducing recoil. So it also reduces the recoil force which acts on the turret and vehicle. First of all, we analyzed the flow-field characteristics of muzzle brake using RAMPANT software. Then we investigated the influence of design parameters of perforated muzzle brake. Sixteen muzzle brakes were tested and evaluated for analyzing their influence on the muzzle brake efficiency. The muzzle brakes were designed to fit on a 40mm gun barrel. The strong dependent parameters of muzzle brake efficiency were the wall thickness(L/d ratio) and the area ratio AR. We designed the perforated muzzle brakes which have 10-20% efficiency. And we proposed a design method of perforated muzzle brake.

• 한국기계가공학회지
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• 제10권4호
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• pp.50-56
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• 2011

Injection molding process is one of the popular manufacturing methods to produce plastic parts with high efficiency and low cost. Ball seat for automobile suspension is made by an injection molding process as a part to support pivot function of ball joint consisted of ball stud and housing. It is necessary for a ball seat to have a dimensional stability in the three dimensional inner area to be contacted with ball stud. In this paper, the dimensional stability of inner surface is indirectly analyzed by checking the difference of inner diameter around the circumferential direction and the thickness variation at the top part of ball seat. Measurement was performed by using the coordinate measuring machine and the fixture to hold ball seat. Optimization of injection molding processes such as injection time, cooling time and temperatures of cylinder barrel was derived to reduce the difference of inner diameter and the thickness variation at the top part of ball seat based on the Taguchi method.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
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• pp.292-297
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• 2001

Twin screw extruders are the heart of the polymer processing industry. They are used at some stage in nearly all polymer processing operations. This paper is concerned with the basic elements of the extruder design. The proper design of the geometry of the extruder screw is of crucial importance to the proper functioning of the extruder. If the material transport instabilities occur as a result of improper screw geometry, even the most sophisticated computerized control system cannot solve the problem. For this purpose, a characteristic design on flights shape of the extruder screw. This paper presents cross section designs of a closely intermeshing twin screw extruder with double-flighted screw elements, and channel depth characteristics for a double flighted corotating self-wiping twin screw extruder.

• 한국정밀공학회지
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• 제20권7호
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• pp.217-226
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• 2003

Twin screw extruders are the heart of the polymer processing industry. They are used at some stage in nearly all polymer processing operations. This paper is concerned with the basic elements of the extruder design. The proper design of the geometry of the extruder screw is of crucial importance to the proper functioning of the extruder. If the material transport instabilities occur as a result of improper screw geometry, even the most sophisticated computerized control system cannot solve the problem. For this purpose, a characteristic design on the screw flights shape of the closely intermeshing co-rotating twin screw extruder. This paper presents design parameters of double flighted screw and triple flighted screw elements, and characteristics of various screw channel area versus screw diameter ratio, K value, in the barrel of screw extruder.

• 비파괴검사학회지
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• 제16권1호
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• pp.46-51
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• 1996

원자로는 압력용기 및 내부 구조물로 구분되어 있다. 내부 구조물들의 경련 열화 현상에 따라 결함이 많이 발생하여 이에 대한 초음파검사가 요구되고 있다. 따라서 원자로 내부 구조물에 대한 초음파검사 현황 및 각각 구조물들의 검사 원리를 기술하였다. 특히 원자로 내부 구조물 중 CRDM, core baffle bolt, core barrel bolt, CRGT-support pin 및 fuel alignment pin에 대한 유럽 및 독일을 중심으로 한 검사 현황 및 검사방법을 간략하게 기술하였다. 이 기술에 대한 지침안(guideline)이 독일, 프랑스, 일본을 중심으로 하여 마련되고 있다.

• 한국소음진동공학회논문집
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• 제21권11호
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• pp.1036-1042
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• 2011

APR1400 RVI CVAP using the non-prototype category II is being conducted to verify integrity of the RVI design and to secure the CVAP technology. The measurement programs are to confirm vibration analysis results for reactor internals during pre-operational and initial startup testing and to determine the safety margin. One of the important basis for the measurement programs is test acceptance criteria. Therefore, this paper is on establishment of response instrumentation test acceptance criteria for APR1400 RVI CVAP. The established acceptance criteria show that the stress criteria of APR1400 RVI are more conservative values than those of the valid prototype plant(Palo Verde unit 1) and, the displacement criteria of the inner barrel assembly and the upper guide structure were established to 0.03 in and 0.01 in, respectively.