• 한국전산구조공학회논문집
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• 제17권4호
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• pp.405-412
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• 2004

재료나 핵연료조사시험에서 다공원통형구조물의 모든 구성품에서 감마열 및 fission과 같은 열원이 발생한다. 본 연구는 조사시험중 다공원통형구조물의 열적건전성을 평가하기 위해 온도분포에 대한 일반해를 구하는데 그 목적이 있다. 다공원통형 구조물의 온도해석을 위해 2차원 열전토 방정식을 이용하였다. 유한요소해석은 ANSYS 6.1을 이용하여 수행하였다. 다공원통형 구조물의 온도해석에서 이론해석결과와 유한요소해석결과는 홀의 개수가 3개 이하에서는 온도가 서로 잘 일치하는 것으로 나타났다. 구조물의 홀 개수가 4개일때, 온도분포해석에 대한 두 결과의 차이가 증가하였다.

• 한국통신학회논문지
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• 제12권2호
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• pp.133-138
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• 1987

본 논문에서는 Re-enterant 공동 공진기의 내부 도체봉 길이 변화에 따른 공진 주파수의 가변특성을 실험정그로 고찰하였다. 실험시 제작된 공진기는 동축 케이블과 원형 도파관을 경합한 형태로서 동축 케이블의 내부 도체봉의 길이를 축방향으로 면화시킬 수 있도록 하여, 내부 도체봉의 임의의 길이에 대한 Tmonq 모드의 공진 주파수를 측정하였다. 경과의 타당성을 입증하기 위해서 실험 경과와 여러 사람들의 이론치를 비교하였다. 본 실험의 결과는 파장계, 공진기?l 증폭기의 공진 회로의 설계및 제작에 활용할 수 있으며 마이크로 웨이브 집적회로(MIC, Microwave Integrated Circuits)나 여과기에 사용되는 유전체 공진기의 공진 주파수를 가변시키는데도 사용할 수 있다.

• 한국정밀공학회지
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• 제17권12호
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• pp.145-150
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• 2000

Micro punching is one of general methods to fabricate simple holes such as permanent ink-jet printer nozzles. A thin punch, that is need for micro punching, usually has been obtained by mechanical machining. There are some method to obtain a thin punch from a cylindrical rod, e.g., microgrinding and WEDG (Wire Electro-Discharge Grinding). Inefficiently, only one punch can be obtained from these machining methods. In contrast with these methods, many punches can be fabricated simultaneously by electrochemical process. Electrochemical process has usually aimed to obtain very sharp probe for atomic force microscopy (AFM) or scanning tunneling microscopy (STM), and it has not been considered the whole shape of a probe in spite of good merits. In this paper, an ultrathin punch with a tapered shape and a cylindrical tip is newly fabricated by electrochemical process.

• 한국기계가공학회지
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• 제19권8호
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• pp.88-93
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• 2020

The goal of this study is to determine the influence of major factors on the spiral surface microparticle injection machining of cylindrical specimens by the statistical method ANOVA. Before the experiment, rod-shaped test specimens and jigs for helical surface spraying were prepared, and the surface roughness was measured with a surface roughness meter. The injection particle, nozzle diameter, and injection pressure were the primary parameters of the experiment. Other factors that were considered were injection height, injection time, revolutions, and feed distance. The surface roughness after machining was measured, and the effects of the surface roughness data on the primary factors were determined with ANOVA.

• 한국주조공학회지
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• 제16권2호
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• pp.141-148
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• 1996

In high chromium cast iron, the control of matrix microstructure as well as carbide structure is important to the performance as a wear resistant material. In this study, 3.0% C-24.0% Cr white cast irons with various molybdenum contents(residual, 1.0%, 3.0% and 5.0%) were solidified conventionally and unidirectionally for studying their effects on the microstructure and hardness. In the conventional casting, two sets of castings were poured from each melt. One set of the castings consisted of cylindrical bars of 10 and 20mm by 155mm long. The second set of the castings was a cylindrical bar of 30mm by 200mm long. On the other hand, a pep-set mold set on the Cu plate was employed to make the solidification unidirectionally. X-ray diffraction method was used to observe retained austenite and carbides in the high chromium cast iron. The morphology of eutectic $M_7C_3$ carbides changed from needle-like type to nodular type with the increase of Mo content. And, the presence of $M_2C$ carbides was identified in the sample where Mo was added over 3.0 %. Primary and eutectic carbides appeared as rod type and corngrain type, respectively in the unidirectionally solidified samples which were cut to parallel to the solidification direction. In the EDX analysis, Cr concentration was higher in the primary and eutectic $M_7C_3$ carbides, Mo in the $M_2C$ carbides, and Fe in the matrix.

• 대한기계학회논문집A
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• 제25권12호
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• pp.1950-1959
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• 2001

An active control of the vibration transmitted by longitudinal load in flight control system is investigated numerically. The flight control system is modeled as a finite, thin shell cylinder with constant thickness. A vibration source is generated by exterior monopole source. Distributed piezoelectric actuator is used to control of the vibration. Thin shell theory is used to formulate the numerical models. The amplitude of vibration at discrete location and power transmission are minimized by analytical optimization method. Genetic algorithm is used as numerical optimization method to search optimal actuator position and size which amplitude of vibration is minimized.

• Applied Microscopy
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• 제20권1호
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• pp.120-127
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• 1990

The zoospores of Polymyxa graminis known as vector of barley yellow mosaic virus(BYMV) were found from the rootlets of diseased barley plants. The X-bodies in the lower epidermis of diseased leaf tissues were reddish under fluorescence microscopy. The shape of virus particles was flexuous rod and 300-1,000 nm in length. The pinwheel structures, cylindrical inclusion bodies, ring-form inclusion bodies, and crystalline lattice-like structure were found together with virus particles in the cytoplasm of diseased leaf tissues. Generally, intracellular organelles in the diseased barley leaf tissues infected with BYMV were either not well-developed or degenerated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.164-167
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• 2005

In this paper, the design and characteristics of a ${\pi}-shaped$ ultrasonic motor which is applicable to optical zoom operation of lenssystem for mobile phone are investigated. Its desi후 and simulation of performances are carried out by FEM (finite element method) commercial software. As a simulation result, by applying voltage with single phase, a combined vibration is produced at the surface of an arm of stator. The prototype of motor is fabricated and its outer size is 8*4*2 $mm^3$ including the cylindrical steel rod of 2 mm in diameter as rotor. The motor exhibits a maximum speed of 500 rpm and a power consumption of 0.3 W when driven at 20 Vpp and 64 kHz.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1244-1249
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• 2008

This paper shows a perfonnance analysis for pneumatic servo cylinder. The pistons without seal have partly cylindrical and conical shapes. 2 dimensional Reynolds equation and FD(finite differential) numerical techniques are utilized for the perfonnance analysis. The relationship among self-centering forces and leakage flows are investigated. Also, optimal design values for a servo cylinder are presented. A prototype of servo cylinder which had rod bearing with four pockets, five pockets, and six pockets was manufactured respectively.

• 한국산업정보학회논문지
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• 제8권1호
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• pp.9-17
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• 2003

본 논문에서는 시간영역 유한차분법(FDTD)을 이용하여 서로 다른 두 원형 도파관의 정합을 위한 원형도파관 정합기를 해석하였다. 축대칭 구조이므로 3차원 문제를 2차원 문제로 변환한 2차원 FDTD 알고리즘을 사용하였고, 상대적으로 반경의 차이가 큰 불연속 도파관에 적용되는 두종류의 정합기를 제안하였다. 하나는 유전체가 부분적으로 채워진 정합기이고, 다른 하나는 테이퍼된 유전체봉이 삽입된 정합기이다. 제안된 정합기에서 정합기의 길이와 직경 및 유전체의 직경 등의 파라미터 변화에 따른 특성을 수치해석하여 비교하였다.