• 소성∙가공
• /
• 제11권7호
• /
• pp.561-568
• /
• 2002

Micro tensile test is the most direct and convenient method to measure material properties such as Young's modulus and fracture strength. It, however, needs more accurate measurement system, mote stable and repetitive alignment and more sensitive gripping than conventional tensile test. Many researchers have put their effort on overcoming these difficulties for tile development of micro tensile tester, fabricating micro specimens of functional materials and measuring their properties. This paper will review the related vigorous researches over the world in the recent decade and explain how to apply them to a design of the fester which is under our own development.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
• /
• pp.629-632
• /
• 2006

The various rib geometry of hybrid fiber reinforced polymer (FRP) reinforcing bars were analyzed by finite element method. From the analysis result, two types of hybrid FRP reinforcing bars such as spiral and cross type with the same dimension of rib geometry were fabricated in this study. To evaluate the bond properties of them, direct pull-out test was performed. All testing procedures including specimens preparation, set-up of test equipments and measuring devices were made in accordance with the recommendations of CSA Standard S806-02. From the test results, it was found that cross type hybrid FRP reinforcing bars showed the highest bond strength than that of the others due to the higher relative rib area.

• 대한치과기공학회지
• /
• 제16권1호
• /
• pp.105-113
• /
• 1994

This study attempted to find out how much stress Dental Technicians of working in Dental Laboratory have built up in the midst of their daily lives are according to their sex, age, duration of work and their kinds of positions. After self-administered questionnaire were distributed by direct to 230 technicians samplely selected from dental laboratories in Seoul and Pusan of whom 163 technicians responded from october 1 through october 13, 1994. Analysis of the data was processed by t-test, $X^2$-test, ANOVA. This results are as follows. 1. Levels of Stress of the total 163 respondents by sex is not higher among male than female(p>.05). 2. Levels of stress - 36.2%(74 Dental technicians) of all Dental technicians were in stress on the whole and 9.2%(15 Dental technicians) of them were in a serious situation by accumulated stress. 3. Realization of stress - 10.1%(16 Dental technicians) of the dental technicians and 89.9%(143 Dental technicians) were found out to be in a dangerous sign or in a situation by accumulated stress. Further studies which a big size and a delicate method of measuring their general characteristics are needed.

• 디지털산업정보학회논문지
• /
• 제13권2호
• /
• pp.53-61
• /
• 2017

How to manage manhole is to estimate the part without observation and maintain the sewer. To get the information about current flow rate, visiting and measuring specific manhole is positively necessary. Also, there are some problems that accurate measurement of flow rate is difficult and obtaining the information about real-time whole flow rate is impossible. This thesis will easily grasp the accurate location and type of manhole to solve the problems, and provide the manhole system conveying information through direct radio communication with a manhole cover to renewal information of manhole properly. Besides, it intends to save the information about management of waterworks, maintenance of facilities, data for flow rate, and structure of manhole. Using these, it is supposed to offer how to handle manhole. Thus, this thesis delivers the information to manhole and into central servers directly without wire and provides the system and management method for effective maintenance of manhole.

• 한국정보통신학회논문지
• /
• 제4권4호
• /
• pp.895-899
• /
• 2000

산란행렬을 이용하여 2단자망 RF 공동공진기의 Q 측정 방법을 제안하였다. 집중소자를 이 용한 등가회로 모델을 이용하여 공동공진기의 Q를 포함한 파라미터의 함수로 산란행렬을 구했다. 산란행렬은 회로망분석기를 이용하여 직접 측정할 수 있다. 제안한 방법으로 측정한 결과는 기존에 잘 알려진 방법과 일치함을 보였다. 제안한 방법의 Q 측정 절차는 기존의 방법에 비해서 간단할 뿐만 아니라 RF 공동공진기가 전자빔을 가속시킬 때 중요한 파라미터인 결합전력비를 구할 수도 있다.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 1990년도 특별강연 및 추계학술발표 개요집
• /
• pp.82-86
• /
• 1990

A new method was investigated to measure the high current in resistance welding processes. A measuring unit was developed by using a strain gage attached on the outer surface of a steel ring. The steel ring was placed around a section of the secondary loop of the welding machine, and was deformed by electro-magnetic forces induced by the high welding current. The circumferential constituent of the ring deformation was then used to obtain a signal voltage proportional to the secondary welding current. The strain gage signal of ring deformation is enough to determine the welding current in resistance spot welding, especially when welded with direct current.

• 대한기계학회논문집A
• /
• 제25권6호
• /
• pp.938-948
• /
• 2001

In this paper, we present an exoskeletal haptic device named SKK Hand Master. This device is directly driven linkages actuated with small ultrasonic motors. By adopting ultrasonic motors that have advantageous features useful for cybernetic actuators, a compact haptic device containing whole driving packages can be established without additional power transmissions such as tendons. Methods for measuring joint postures and joint torques are developed and a new control strategy called PWM/PS is proposed to overcome intrinsic disadvantages such as hysteresis. Issues regarding design and construction of the device are addressed and several results of experiments for the evaluations of performance are included.

• 국제학술발표논문집
• /
• The 1th International Conference on Construction Engineering and Project Management
• /
• pp.908-912
• /
• 2005

Construction Cost Indices are values for measuring fluctuations in direct construction costs which include material costs, labor costs, and equipment costs for construction operations. In Korea, Korea Institute of Construction Technology (KICT) has been assessing and announcing these indices since January, 2004. The main goals of this paper are to look over the calculation process for those indices and then present the trend in construction costs according to the types of facilities with the past construction cost index data. Also, this paper traces the origin of the occurrence of significant changes on those indices through the further analysis of the trend. In addition, this paper shows the practicality of the indices and the way how to put them to practical use. An alternative estimate method using the indices is suggested for compensating the changes of construction costs caused by price fluctuations.

• 수산해양기술연구
• /
• 제50권1호
• /
• pp.67-74
• /
• 2014

Most of steam power plants in Korea are using the method of heating the feed water whenever the ambient temperature around the power plant area below $5^{\circ}C$ to prevent freezing water flowing in the pipe in winter time. But this kind of heat supplying system is not useful to save energy. If we take the method that the temperature of the each pipe is controled by direct measure of temperature by attaching sensor on the outside surface of the feed water tubes, then we can expect that a plenty of energy can be saved. In this study, the computer simulation is used to compare the energy consumption loads of both systems. Energy saving rate is calculated for the location of Incheon area in winter season. Four convection heat transfer coefficients for the ambient air and three initial flowing water temperature inside the tube were used. The result shows that the temperature control system using sensor represents more than 95% of energy saving rate in Incheon area. Even in the severe January weather condition, the energy saving rate is almost 75% in two days basis and even 83% in one day basis.

• 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.