• Nuclear Engineering and Technology
• /
• 제30권5호
• /
• pp.452-461
• /
• 1998

The pin power distribution is determined by analyzing the rotational gamma scanning data for 36 element fuel bundle of HANARO. A fission monitor of Nb$^{95}$ is chosen by considering the criteria of the half-life, fission yield, emitting ${\gamma}$-ray energy and probability. The ${\gamma}$-ray spectra were measured in Korea Atomic Energy Research Institute(KAERI) by using a HPGe detector and by rotating the fuel bundle at steps of 10$^{\circ}$. The counting rates of Nb$^{95}$ 766 keV ${\gamma}$-rays are determined by analyzing the full absorption peak in the spectra. A 36$\times$36 response matrix is obtained from calculating the contribution of each rod at every scanning angle by assuming 2-dimensional and parallel beam approximations for the measuring geometry. In terms of the measured counting rates and the calculated response matrix, an inverse problem is set up for the unknown distribution of activity concentrations of pins. To select a suitable solving method, the performances of three direct methods and the iterative least-square method are tested by solving simulation examples. The final solution is obtained by using the iterative least-square method that shows a good stability. The influences of detection error, step size of rotation and the collimator width are discussed on the accuracy of the numerical solution. Hence an improvement in the accuracy of the solution is proposed by reducing the collimator width of the scanning arrangement.

• 대한화학회지
• /
• 제18권2호
• /
• pp.143-149
• /
• 1974

從來에 開發된 cryoscopy 裝置는 手動型으로서 一回測定에 所要되는 最少 한時間을 두사람이 測定에 꼬박 關與하여야 하는 不便을 갖는다. 뿐만 아니라 手動攪拌에 依한 不規則的攪拌速度에서 오는 誤差나, Beckmann 溫度計의 感溫部가 나타내는 큰 熱容量 및 判讀時의 視角差차와 波勞度에서 오는 誤差等이 不可避하게 作用한다. 그러므로 本 硏究에서는 이들 誤差를 減少시키기 爲하여 다음과 같이 裝置改良에 依한 自動測定法을 開發하였다. (1) 水槽溫度의 自動精密調節 (2) 感溫部의 熱容量이 매우 작은 thermistor에 依한 溫度測定 (3) 檢流計의 反射光을 感光紙에 照射시켜 轉移溫度를 自動記錄하는 이른바 溫度自動記錄裝置의 開發 (4) 攪拌裝置의 自動化 한편 從前부터 使用되어 오는 10水和物 芒硝는 加入時 一部가 容器壁에 묻어 反應에 關與하지 못하며, 또한 10水和物화물을 部分的으로나마 脫水되지 않은채 保存하여 測定에 使用하기는 어려우므로 本硏究에서는 無水芒硝를 써서 하는 實驗條件을 아울러 究明하였다.

• Steel and Composite Structures
• /
• 제18권3호
• /
• pp.673-691
• /
• 2015

In this paper we are particularly focusing on the dynamic crack fatigue life of a 25 m length wind turbine blade. The blade consists of composite materiel (glass/epoxy). This work consisted initially to make a theoretical study, the turbine blade is modeled as a Timoshenko rotating beam and the analytical formulation is obtained. After applying boundary condition and loads, we have studied the stress, strain and displacement in order to determine the critical zone, also show the six first modes shapes to the wind turbine blade. Secondly was addressed to study the crack initiation in critical zone which based to finite element to give the results, then follow the evolution of the displacement, strain, stress and first six naturals frequencies a function as crack growth. In the experimental part the laminate plate specimen with two layers is tested under cyclic load in fully reversible tensile at ratio test (R = 0), the fast fracture occur phenomenon and the fatigue life are presented, the fatigue testing exerted in INSTRON 8801 machine. Finally which allows the knowledge their effect on the fatigue life, this residual change of dynamic behavior parameters can be used to predicted a crack size and diagnostic of blade.

• 한국항해학회지
• /
• 제3권1호
• /
• pp.47-77
• /
• 1979

A microwave Navigational Aid system is suggested suitable for fishing boats too small to be equipped with Radar or Radio-Direction-Finder. The system proposed here is similar to that of Talking-Beacon developed in Japan, but the distinctive modification proposed is that an increase of sixteen times in peak transmitting power, thus an accompanying increase of coverage, is achieved with the same mean transmitting power as that of Japan without sacrificing the clearness of azimuth information, by adopting a pulse repetition modulation instead of pulse width modulation as in Japan system. An experimental land station transmitter of transmitting frequency of 9, 370MHz and of peak power of 35kw with a microwave beam of 1 degree in horizontal width and 7 degrees in vertical width rotating once every three minutes, and also an experimental receiver of 20-dB in sensitivity and of an assumed cost of 100 dollars, operated by a 12 volts battery source are made, and the sail test results are reported showing that a bearing infromation of an accuracy of within two degrees can be obtainable every three minutes at a distance of as far as 24 miles from the transmitter if the transmitter is located as high as 100 meters above sea-level.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.245-247
• /
• 2002

The paper represents the effects of the drive-in process parameters on the residual stress profile of the p+ silicon film. For the quantitative determination of the residual stress profiles, the test samples are doped via the fixed boron diffusion process and four types of the thermal oxidation processes and consecutively etched by the improved process. The residual stress measurement structures with the different thickness are simultaneously fabricated on the same silicon wafer. Since the residual stress profile is not uniform along the direction normal to the surface, the residual stress is assumed to be a polynomial function of the depth. All of the coefficients of the polynomial are determined from the deflections of cantilevers and the displacement of a rotating beam structure. As the drive-in temperature or the drive-in time increases, the boron concentration decreases and the magnitude of the average residual tensile stress decreases. Also, near the surface of the p+ film the residual tensile stress is transformed into the residual compressive stress and its magnitude increases.

• 정보저장시스템학회논문집
• /
• 제7권1호
• /
• pp.19-24
• /
• 2011

Holographic Data Storage System, one of the next generation data storage devices, is a 2-dimensional page oriented memory system using volume holograms in writing and retrieving process. Recently photopolymer with disc type substrate was selected as a media for the Holographic Data Storage System. The disc tilt occurs when the media rotates and the external disturbance applies. The disc tilt causes the change of the angle between the reference beam and the media, the data cannot be retrieved with the right angle or other data page is retrieved. The tilt is generated in a 2-axis direction (tangential, radial). The tangential tilt direction is the same with the multiplexing plane, while the radial tilt direction is a perpendicular to the multiplexing plane. In this research we propose 2-axis tilt angle servo system. The tilt errors are measured by using external photo detector and the additional red laser. Then the tangential direction tilt is compensated by using the galvano mirror. Also the radial direction tilt is compensated by the rotating prism between the relay lens in the reference field. Finally we confirm the compensation results through the Signal to Noise Ratio(SNR) and Bit Error Rate(BER).

• 한국광학회지
• /
• 제14권3호
• /
• pp.260-265
• /
• 2003

미세하게 진동하는 물체의 변위를 비접촉식으로 측정할 수 있는 광학계를 설계하고 제작하였다. 도플러효과에 의한 방법과는 달리, 하나의 볼록렌즈를 이용하여 물체 표면에 비스듬하게 입사하여 물체 표면에서 반사되는 광점의 위치 변화를 PSD(position-sensitive detector)로 검출하였다. 이러한 방법으로 전체적인 장비의 크기를 작게 하였고 빠른 응답 속도를 구현하였다. 본 장비는 $\pm$1.0 $\mu\textrm{m}$의 분해능을 나타내었으며, 스피커의 진동 실험 및 CD-ROM안에서 회전하는 C교의 진동을 측정하였다.

• 한국광학회지
• /
• 제9권1호
• /
• pp.25-30
• /
• 1998

본 논문에서는 다중모드 광섬유에서 발생하는 모드스페클 패턴을 이용한 M개의 입력단과 N개의 출력단 사이의 간단한 광연결 방법에 관하여 기술하였다. 적절히 여기된 모드스페클 패턴을 목적지 코드로 사용하고, M개의 홀로그램을 중첩기록한 Vander Lugt 정합필터를 사용하여 수신되는 모드스페클 패턴을 분리 검출함으로써 nonblocking 완전광연결이 가능함을 설명하였다. 광섬유에 입사되는 빔입사각을 바꾸어주거나, 입력광의 편광방향을 바꾸어주면서 출력단에 발생되는 모드 스페클 패턴들의 직교특성을 조사하였다. 임의의 M * N 광연결이 가능함을 보이기 위한 기초 실험으로 코어직경이 50.mu.m인 경사형 굴절율 분포의 4 * 4 다중모드 광섬유 결합기를 사용하여 1 * 2 광연결과 2 * 1 광연결 실험을 수행하였다.

• Advances in aircraft and spacecraft science
• /
• 제10권1호
• /
• pp.19-49
• /
• 2023

The present study proposes a theoretical and numerical investigation on the dynamic response behaviour of a functional graded (FG) ceramic-metal tapered rotor shaft system, by the differential quadrature finite elements method (DQFEM) to identify the natural frequencies for modelling and analysis of the structure with suitable validations. The purpose of this paper is to explore the influence of heat gradients on the natural frequency of rotation of FG shafts via three-dimensional solid elements, as well as a theoretical examination using the Timoshenko beam mode, which took into account the gyroscopic effect and rotational inertia. The functionally graded material's distribution is described by two distribution laws: the power law and the exponential law. To simulate varied thermal conditions, radial temperature distributions are obtained using the nonlinear temperature distribution (NLTD) and exponential temperature distribution (ETD) approaches. This work deals with the results of the effect on the fundamental frequencies of different material's laws gradation and temperature gradients distributions. Attempts are conducted to identify adequate explanations for the behaviours based on material characteristics. The effect of taper angle and material distribution on the dynamic behaviour of the FG conical rotor system is discussed.

• 한국광학회지
• /
• 제19권3호
• /
• pp.182-186
• /
• 2008

프리즘 분광기는 굴절률 측정을 위한 표준 장치로, 대학교 실험실에서 사용되는 전형적인 실험 기구이지만, 정렬할 때 많은 주의가 요구되고 장치의 견고함에 비해 측정된 굴절률의 정확도는 떨어진다. 이러한 단점을 보완한 최대 최소 편향법은 회전 플랫폼과 길이 측정용 테이프로 저렴하게 장치가 구성되고 넓은 스크린을 활용하여 비교적 정확하게 굴절률을 측정할 수 있다. 본 연구에서는 한변이 26 mm인 속이 빈 등변 프리즘을 제작하여 글리세린($C_3H_5(OH)_2$), 사염화탄소($CCl_4$), 아닐린($C_6H_4NH_2$), 이황화탄소($CS_2$), 크실렌($C_6H_4(CH_3)_2$) 등의 액체를 채워, He-Ne 레이저의 파장 632.8 nm와 $YVO_4$ 레이저의 파장 532 nm에 대해 프리즘 분광기와 최대 최소법으로 이들 액체의 굴절률을 측정하였다. 측정결과 최대 최소법으로 얻어진 데이터가 프리즘분광기에 의해 얻어진 데이터보다 더 정확하고 정밀함을 확인하였다.