• Korean Journal of Mathematics
• /
• 제25권1호
• /
• pp.37-43
• /
• 2017

We study the existence of positive solutions of second order nonlinear separated boundary value problems of superlinear as well as sublinear type without imposing monotonicity restrictions on the problem. The type of problem investigated cannot be analyzed using the linearization about the trivial solution because either it does not exist (the sublinear case) or is trivial (the superlinear case). The results follow from a known fixed point theorem by noticing that the concavity of the solutions provides an important condition for the applicability of the fixed point result.

• 전자공학회논문지D
• /
• 제34D권11호
• /
• pp.9-19
• /
• 1997

By noticing that most waveguide devices were connected to power source through coaxial line, three dimentional finite element analysis using TEM mode incident was tried. When tEM mode was used, being dissimilar to TE$_{10}$ mode incident, analysis model of TEM mode incident has almost the same geometry with real products. Therefore, the degree of trust about analysis result is improved. Reflection coefficients of coaxial line, W/G adaptor, magnetron obtained by simulation was compared with experimental results.

• East Asian mathematical journal
• /
• 제27권5호
• /
• pp.539-543
• /
• 2011

In this paper, we consider an optimization problem which consists a nonconvex quadratic objective function and two nonconvex quadratic constraint functions. We formulate its dual problem with semidefinite constraints, and we establish weak and strong duality theorems which hold between these two problems. And we give an example to illustrate our duality results. It is worth while noticing that our weak and strong duality theorems hold without convexity assumptions.

• 대한기계학회논문집A
• /
• 제20권5호
• /
• pp.1372-1381
• /
• 1996

As recieved boiler tuve steel was aged artificially at $650^{\circ}C$ and$690^{\circ}C$ for various time duration to simulate the material deterioration which could be occurred during the operation of fossiol power plants. And the tensile tests, the microhardness tests and the characterization of carbides formed in the aging process were performed to asses the relationship between the mechanical properties and the effect of thermal aging. Furthernore, the amout of Mo-rich carbide were investigated by ondestructive method by noticing the fact that formation of Mo-rich carbide were investigated by ondestructive melthod by noticing the fact that formation of Mo-rich carbides($Mo_6C$) which stabilizes lastly affects the mechanical properties. It was known that the microhardness results of service exposed materials were similar to the ones which are aged at $650^{\circ}C$. The room temperature measurement showed small variation in the yield points and ultimate strength in materials aged at $650^{\circ}C$. Those properties at $540^{\circ}C$ showed the abrupt decrease compared with as received material even if short aging time. And it was found that $650^{\circ}C$ $690^{\circ}C$ aging cause different effects on mechanical properties, although the temperature time parameters(LMP;Larson-Miller parameter) are same. And it was concluded that the aigng at $650^{\circ}C$ is more appropriate to simulate the service exposed condition. Finally, the relationship between high temperature tensile properties and Ip values were established, which offers a potential way of reliability tests onthe power plant components.

• 한국생산제조학회지
• /
• 제7권1호
• /
• pp.104-111
• /
• 1998

This study solves the inverse kinematics problem of industrial FANUC robot. Because every joint angle of FANUC robot is dependent on the position of end-effector and the direction of approach vector, arm metrix T6 is very complicated and each joint angle is a function of other joint angles. Therefore, the inverse kinematics problem can not be solved by conventional methods. Noticing the fact that if one joint angle is known, the other joint angles are calculated by the algebraic methods. $ heta$1 is calculated using neumerical analysis method, and solves inverse kinematics problem. This proposed method, in this study, is more simpler and faster than conventional methods and is very useful in the real-time control of the manipulator.

• 영어어문교육
• /
• 제18권1호
• /
• pp.171-195
• /
• 2012

While noticing that there is insufficient interest in the assessment of EFL learners' vocabulary levels or sizes, the researchers developed two tests identical in form (Forms A and B) to assess the lexical knowledge of Korean university learners at the $1^{st}{\sim}10^{th}$ 1,000 word bands by adapting a pre-established vocabulary levels test (VLT). Of equal concern was to investigate if the VLT was equally a valid and reliable instrument to be used on measuring the lexical knowledge of EFL learners. The participants were 804 university freshmen enrolled in a General Education English Course from four different colleges. The learners were asked to respond to either Form A or B. While scores generally fell towards the lower frequency bands, multiple regression found the Korean College Scholastic Ability Test (CSAT) to be a significant variable for predicting the learners' vocabulary sizes. From a methodological perspective, however, noticeable differences between Forms A and B could be found with item response theory analysis. The findings of the study provide suggestions on how future VLT for testing EFL learners may have to be redesigned.

• 대한전기학회논문지
• /
• 제32권7호
• /
• pp.227-233
• /
• 1983

Noticing that action of gaseous phase in insulating oil concerns to the discharging characteristics, I investigated the smalness pressure effects on quantity of the partial discharge and discharging pulse frequency. Tests are carried out between the niddle points in insulating oil at pressure being changed by gradual charge of inert gas Ar. At pressure as low as of 0.1-0.5 torr pulse frequency and maximum partial discharge reach peak while at pressure haigher than 20 torr no pulse is observed. The fact that pulse frequency has peak value at certain presure, which is changed either by charging Ar or by adding oil, implies that the action of gaseous phase depends on pressure. Test results are that partial discharge pulse are governed by pressure of Ar-charged oil, and less partial discharge pulses correspond to smaller bubbles whereas more partial descharge pulses correspond to larger bubbles.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 춘계학술대회 논문집
• /
• pp.309-313
• /
• 2002

This paper presents an artificial intelligent model for a soccer robot. We classified soccer robot as artificial intelligent model into three elemental groups including instinct intuition and reason. Instinct is responsible for keeping the ball, walking or rushing toward the ball. This is very simple fundamental action without regard to associates and enemies. Intuition contributes to the faster/slower moving and simple basic turning to get near to the ball and to make a goal noticing associates and enemies. Reason is the most intelligent part, the law of reason is not simple relatively with instinct and intuition. We shall expect to design the best law of reason for a soccer robot some time. We also compared nerve system and muscles of human being model with controller and motors of a physical soccer robot model individually. We had designed several algorithms and made programs to investigate effects and control soccer robot.

• 한국항해학회지
• /
• 제9권2호
• /
• pp.27-41
• /
• 1985

The transportation productivity is the throughput of utility per locations of resources and is able to be brought forth by using transportation mode. Therefore, Oil energy is necessary for using the transportation mode that is mainly consisted of four parts trucks, railroad, ship and aircraft, and Oil quantity used for such modes is not respectively same. Noticing Such a Point, the purpsoe of this paper is to reaserch the transportation mode of convertable cargoes and to minimize energy consumption quantity by adopting such a mode. We must ttend to Energy-Intensity, Transportation, Distance and cargo quantity for selecting the transport mode to energy consumption and the minimization of transportation energy consumption is concluded in the next LP Problem. As above mentioned, we can find the solution of Xij by the LP when Xij is transportation cargo per routes, and fullfil the minimization of Energy Consumption.

• 대한조선학회논문집
• /
• 제40권1호
• /
• pp.55-62
• /
• 2003

This study has investigated physical and chemical properties of FRP waste, has manufactured polymer cement mortar using a crushed waste with sand and has evaluated its capability to develop the economical waste recycling technology. The study has investigated tension strength, hardness test and impact test as physical properties and also thermogravimetric characteristics and analyzed infrared spectroscope as chemical properties. Then the study has manufactured polymer cement mortar and has analyzed how the FRP waste fine aggregate replacement ratio has an effect on compression strength. Noticing admixture can complement strength drop occurred by the FRP waste fine aggregate replacement, the study examined an optimum rate of admixture addition and its reaction through electron microscope photos.