• International Journal of Korean Welding Society
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• v.3 no.1
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• pp.39-44
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• 2003

The welded specimens were made by butt welding of the 2 wires of 50mm length using the pulsed YAG laser. The laser welded wires were tested for investigating the shape memory effect and the ability of super elasticity. The fatigue properties of the welded wires were investigated using the rotary bending fatigue tester specially designed for wires. Moreover, the effect of defocusing distance during laser welding on the static and fatigue properties was Investigated. The shape memory effect and super elasticity of the laser welded wires were approximately identical with that of base metal at the test temperature below 353K. However, the welded wires were broken within elastic limit at the test temperature above 353k. Under the cyclic bending loading conditions, the welded wires could be useful only below the elastic limit, while the base metal had sufficient fatigue life even the stress induced M-phase region. The fatigue strength of the welded wires was about half of that of the base metal. The deterioration of the static and fatigue properties in the welded wires was proven to be from the large difference of the transformation behavior between the base metal and welded part that is caused by vaporization of Ni-content at the welded part during the welding process. The defocusing distance below 3mm acted more largely on lowering the strength of the welded wires than that of 6mm or 8mm.

• Korean Journal of Veterinary Research
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• v.25 no.2
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• pp.133-144
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• 1985

The changes of acid-base status in vitro of the venous blood for 24 hours in ten Korean native goat were investigated. The acid-base parameters were measured within ten minutes after collection of the blood, and every hour during the first six hours and finally after twenty four hours of storage. Blood samples were stored at two different temperatures ($0-4^{\circ}C$ and $21-24^{\circ}C$). Twelve goats were induced acute acid-base disturbances by intravenous infusion of either hydrochloric acid or sodium bicarbonate and inhalated with $CO_2$ gas mixture (20% $CO_2$, 80% $O_2$) or hyperventilation were performed by means of respirator. The results were as follows; 1. Blood samples could be stored during the first two hours in ice water ($0-4^{\circ}C$) and one hour at room temperature without significant changes in pH. The magnitudes of changes were similar to those of cow, and lower than those of men and dogs. 2. The mean values of acid-base parameters in normal goat were arterial pH, 7.40; $P_{CO_2}$, 35.4mmHg; $HCO_3{^-}$, 21.8mEq/L. 3. Both the base excess and the bicarbonate showed high correlation (r=0.99) during the metabolic disturbance and were represented as $B.E.=1.38\;HCO^-{_3}-29.7$. 4. The slope of blood buffer curve obtained from the in vivo experiment was 16.3mEq/L/pH. 5. The magnitudes of changes in hydrogen ion concentration per unit change of $P_{CO_2}$ were 0.8nM/mmHg in hypercapnia and 1.0nM/mmHg in hypocapnia. 6. The ranges of acid-base parameters in normal goat urine were pH, 6.0-8.1; $P_{CO_2}$, 42-61mmHg; $HCO_3{^-}$, 2-110mEq/L. The concentration of potassium was higher (60-200mEq/L), and that of sodium was lower (8-70mEq/L) than those of human urine.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.349-356
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• 2002

There has been an increasing trend toward the use of pushover analysis as a tool for evaluating the seismic resistant and safety of a building structure in the performance based earthquake engineering field. The ATC-40 document proposed a nonlinear static procedure based on the Capacity Spectrum Method to determine earthquake-induced demand given the structure pushover curve, which a curve representing base shear versus roof displacement. However, the procedure is conceptually simple, iterative and time consuming method and may sometimes lead to no solution or multiple solutions. A new improved method of seismic performance evaluation for moment frame building, which take into account the previously mentioned deficiencies of currently used elastic design procedures, is presented in this paper. The results of nonlinear static and nonlinear time history analysis of an example high-rise steel moment frame designed by the proposed method are presented and discussed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1451-1459
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• 1995

The objective of this paper is to evaluate the material properties of SA312 TP316 and SA312 TP304 stainless steels and their associated welds manufactured for safety injection system of Yonggwang 3,4 nuclear generating stations. A total of 62 tensile tests and 46 fracture toughness tests were conducted and the effects of various parameters such as pipe size, crack plane orientation, tests were conducted and the effects of various parameters such as pipe size, crack plane orientation, test temperature, welding on material properties were discussed. Test results show that the effect of test temperature on fracture toughness was significant while the effects of pipe size and crack plane orientation on fracture toughness were negligible. Fracture toughness of the weld metal was in general higher than that of the base metal.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.815-818
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• 1998

The Insulated Gate Bipolar Transistor has the characteristics of MOSFET and BJT. The characteristics of proposed device exhibit high speed switching, the voltage controlled property, and the low ON resistance. This hybrid device has been used and developed continuously in the power electronic engineering field. We can simulate many IGBT circuits, such as the motor drive circuit, the switching circuits etc, with PSpice. However, some problems in PSpice is that the IGBT is old-fashioned and is very difficult to get it. In this paper, the IGBT in PSpice is considered as the basic structure. We changed the valuse of base width, gate-drain overlaping area, device area, and doping concentration, then calculated MOS transconductance, ambipolar recombination lifetime etc. Using this resultant parameter, we could predict the transient response characteristicsof IGBT, for examplex, voltage overshoot, the rising curve of voltage, and the falling curve of current.

• Honam Mathematical Journal
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• v.41 no.4
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• pp.683-695
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• 2019

In the present paper, we study curves in 𝔼³ with density $e^{ax^2+by^2}$, where a, b ∈ ℝ not all zero constants and give the parametric expressions of the curves with vanishing weighted curvature. Also, we create ruled surfaces whose base curves are the curve with vanishing weighted curvature and the ruling curves are Smarandache curves of this curve. Then, we give some characterizations about these ruled surfaces by obtaining the mean curvatures, Gaussian curvatures, distribution parameters and striction curves of them.

• Journal of Welding and Joining
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• v.11 no.1
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• pp.42-51
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• 1993

In this study, investigations were conducted in calculating parameters of elastic-plastic fracture mechanics using single specimen. The validity of these testing methods was judged by the confirmation of multiple specimen method of stop block test. The results were as follows: In order to measure a fracture toughness using the instrumented impact test, two general requirement must be considered; One, setting up proper impact velocity considered the effect of loading and the other, the necessity of low blow test for obtaining true energy by the compliance correction. It was possible to detect a crack initiation point by calculating the compliance changing rate from a load-defection curve. Criterion of a stable crack growth, $T_{mat}$ could be estimated by using key-curve method for a base metal. and combining Kaiser's rebound compliance with Paris-Hutchison's $T_{appl}$ equation for the brittled zone of welding heat affected.at affected.d.

• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.60.1-60.1
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• 2010

본 연구에서는 년 최대 홍수량의 발생에 대한 대안으로 사용하는 PMF 추정에 관한 내용을 중심으로 분석하고자 한다. PMF를 산정하는 매개변수 도달시간(Time of concentration, TC)과 저류상수(Storage constant, K), 유출곡선번호(Runoff curve number, CN), 감수상수(Recession constant, RC), 초기손실(Initial loss, IL), 초기기저유량(Initial base flow, IBF), Threshold(TQ)들 중 CN값을 고정 하였을 때와 고정하지 않았을 때로 나눠 산정된 각각의 PMF와 기 발표된 PMF와 상호비교 분석을 통해 신뢰성 있는 분석방법을 제시하였다.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.7
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• pp.409-416
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• 2004

This paper presents the selection method o( the input current wave forms for the thrust force ripple of linear pulse motor (LPM). We have developed and tested a prototype 2-phase 4-poles LPM with the permanent magnet and its control driver. To obtain the thrust performance curve of LPM, the performance curve at the air gap and the thrust are calculated and estimated by the analytical method on the base of the magnetic equivalent circuit and the finite element method. And, the thrust characteristics at the static operation state are analyzed and experimented with the respect to the input wave forms such as the rectangular, the triangular micro-step and the sine micro-step wave forms to investigate the thrust ripple and the vibration effects of LPM.

• Journal of Industrial Technology
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• v.1
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• pp.39-45
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• 1981

The typical characteristic shape of the Koryo inlaid celadon Maebyong was reviewed and the symmetry of S curve was analyzed by the method of geometric basis. The contours of Maebyongs sampled were drawn and divided with geometric rectangular proportion. The analytical results showed the static and dynamic symmetric of the vase and the ratios of height and base of the rectangles established for the analysis of their shapes were almost 1:1, 1:${\sqrt{2}}$ and 3:5(known as the Golden Ratio). The excellent beauty of the curve was principally caused by the balanced and harmonius division of the proportional rectangles. The contour line was developed along with the logarithmic spiral modified and introduced lately into the shape of Yi dynasty's liquor bottle.