• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 춘계학술대회 and 제3회 신약개발 연구발표회
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• pp.50-62
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• 1994

Opium, morphine and rotated natural and synthetic opiates have been used since antiquity, and to the present, for the relief of moderate and severe pain. Morphine and pharmacologically related drugs, however, produced an array of undesired or dangerous side effect that limit their use as analgesics. Prominent among the limiting side effects are constipation, respiratory depression, release of prolactin, and liability for the production of drug dependence. It was our aim to develop, if possible, a drug or class of drugs with analgesic activity similar to that of morphine, but without the serious side effects associated with morphine. Our overall strategy was to take advantage of advancing knowledge concerning multiple types of opioid receptors, to develop ligands selective for the delta type receptors, to determine whether delta receptor agonists offer advantages over mu agonists, then to design compounds with pharmacokinetic properties compatible with practical therapeutic application. All but the last of these objectives have been realized.

• The Korean Journal of Ceramics
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• 제4권2호
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• pp.151-155
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• 1998

The total electrical conductivity, ionic conductivity, and nonstoichimetry of a new cathode material $Y_{1-x}Ca_xFeO_{3-\delta}$ (x=0.1) were measured as functions of temperature ($900\leqT/^{\circ}C\leq1100$) and oxygen partial pressure $(10^{-6}\leqPo_2/atm\leq0.21$). Isothermal variations of these properties with $Po_2$ support that the majority type of ionic defects are anti-Frenkel disorder which, however, has seldom been considered for perovskite-based oxides. The results are discussed in comparison with those reported on similar oxides.

• Journal of Power Electronics
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• 제9권5호
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• pp.667-678
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• 2009

The PWM (Pulse Width Modulation) control signals have a drawback in that their power spectrum tends to be concentrated around the switching frequency and the resulting harmonic spikes cause an EMI (Electromagnetic Interference) and switching losses in semiconductors, etc. The SDM (Sigma-Delta Modulation) is a type of switching modulation used to reduce these harmonic spikes, and several SDM schemes are investigated in this paper. In the DSDM (Dithered SDM), the SDSDM (Space-Dithered SDM) and TDSDM (Time-Dithered SDM), the signals are classified by the location of their random dither additions. In these schemes, the switching frequency is spread by a random dither generator placed on the input or the output parts. Experimental results are presented where the advantages of the new proposed CDSDM (Combined Dithered SDM) are confirmed by applying to a buck converter.

• 한국농공학회논문집
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• 제51권6호
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• pp.83-90
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• 2009

This study was carried out to evaluate the vertical stress properties in sandy soil according to changes of loading type in soil bin compacted three layers. The following conclusions and comparisons have been made based on careful analysis from theoretical and experimental methods. : When sandy soil subjected to cycle-loading, compression of foundation and diffusion of vertical stress increment(${\Delta}{\sigma}_2$) were influenced by magnitude of loading plate. When sandy soil subjected to reloading after removing of pre-loading, the distribution of ${\Delta}{\sigma}_2$ depth at one time of loading plate width was different from its distribution at more deep point cause of load hysteresis, so in case of design of structure, the effect of ${\Delta}{\sigma}_2$ as depth must be considered. The increment of vertical stress will be different as loading condition and foundation depth, the loading condition must be considered in case of structure design.

• 대한수학회보
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• 제50권4호
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• pp.1061-1067
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• 2013

In this paper, we study surfaces of revolution without parabolic points in 3-Euclidean space $\mathbb{R}^3$, satisfying the condition ${\Delta}^{II}G=f(G+C)$, where ${\Delta}^{II}$ is the Laplace operator with respect to the second fundamental form, $f$ is a smooth function on the surface and C is a constant vector. Our main results state that surfaces of revolution without parabolic points in $\mathbb{R}^3$ which satisfy the condition ${\Delta}^{II}G=fG$, coincide with surfaces of revolution with non-zero constant Gaussian curvature.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2007년도 춘계학술대회
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• pp.221-225
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• 2007

We have prepared $\delta$-phase SbTe alloy with various Sb contents of 64, 72, and 76 at. % and investigated the phase change temperature, the crystal structures of $\delta$-phase SbTe alloy, and determined the ovonic threshold switching voltages with edge contact type phase transition dimensions. As a result, the crystallization temperature is slightly reduced from 126 to $122^{\circ}C$, whereas the melting temperature is not changed. The ovonic threshold switching voltage is reduced from 1.6 to 0.9 V as increasing the Sb content from 64 to 76 at. %. It is found that the reductions of crystallization temperature and the ovonic threshold switching voltage are closely related with the interplanar spacing between adjacent atomic layers and the stacking number of atomic layers in a unit cell.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.544-547
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• 1989

The introduction of resonant link inverters has allowed the use of much higher switching frequencies in induction motor current regulators. The resonant link inverter,however, requries the use of discrete time switching strategies. This type of controller,while giving the best possible performance, is difficult to implement, since motor parameters must be calculated or measured. The delta modulated current regurator (DMCR) has been introduced as a controller without additional state feedback. A discrete pulse modulated current regulator which controls load current is introduced in the paper.

• Journal of Welding and Joining
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• 제28권3호
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• pp.86-91
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• 2010

Stainless steel sheets are widely used as the structural material for the railroad cars and the commercial vehicles. These kinds structures used stainless steel sheets are commonly fabricated by using the gas welding. For fatigue design of gas welded joints such as fillet and plug type joint, it is necessary to obtain design information on stress distribution at the weldment as well as fatigue strength of gas welded joints. And also, the influence of the geometrical parameters of gas welded joints on stress distribution and fatigue strength must be evaluated. the ${\Delta}P-N_f$ curves were obtained by fatigue tests. Using these results, ${\Delta}P-N_f$ curves were rearranged in the ${\Delta}{\sigma}-N_f$ relation with the maximum stress at the edge of fillet welded joint.

• 열처리공학회지
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• 제2권4호
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• pp.19-26
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• 1989

Fundmental fatigue crack propagation tests with C-T type specimens were conducted at various load ratios (R) such as 0.1, 0.3 and 0.5 in T6 and Thermomechanically treated (TMT) conditions of 7039 Al alloy. Better mechanical properties from monotonic test as well as fatigue crack propagation were obtained by TMT process owing to uniform distribution of fine microstructures and non-existence of precipitation free zone (PFZ). Through the measurement of Kop and ${\Delta}K$ at various R the concept of effective stress intensity factor range ratio, U was reviewed to asses the load ratio effect on fatigue crack propagation. A relationship between U and variables such as ${\Delta}K$ and R was obtained empirically. This may enable us to predict ${\Delta}K_{eff}$ that is of critical importance for prediction of fatigue crack propagation rate.

• 한국자동차공학회논문집
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• 제18권4호
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• pp.127-131
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• 2010

Stainless steel sheets are widely used as the structural material for the railroad cars and the commercial vehicles. These kinds of structures used stainless steel sheets are commonly fabricated by using the gas welding. For fatigue design of gas welded joints such as fillet and plug type joint, it is necessary to obtain design information on stress distribution at the weldment as well as fatigue strength of gas welded joints. And also, the influence of the geometrical parameters of gas welded joints on stress distribution and fatigue strength must be evaluated. Thus, in this paper, ${\Delta}P-N_f$ curves were obtained by fatigue tests. Using these results, ${\Delta}P-N_f$ curves were rearranged in the. ${\Delta}{\sigma}-N_f$ relation with the hot spot stresses at the gas welded joints.