• Corrosion Science and Technology
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• 제2권3호
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• pp.141-147
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• 2003

Sputter-deposited Nb-Al-Cr alloys. $3-5{\mu}m$ thick, have been prepared on quartz substrates as oxidation-and sulfidation-resistant materials at high temperatures. The oxidation or the alloys in the $Ar-O_2$ atmosphere of an oxygen partial pressure of 20 kPa follows approximately the parabolic rate law, thus being diffusion controlled. Their oxidation rates are almost the same as or even lower than those ofthc typical chromia-forming alloys. The multi-lavered oxide scales are formed on the ternary alloys. The outermost layer is composed of $Cr_2O_3$, which is"mainly responsible for the high oxidation'resistance of these alloys. In contrast to sputter-deposited Cr-Nb binary alloys reported previously, the inner layer is not porous. TEM observation as well as EDX analysis indicates that the innermost layer is a mixture of $Al_2O_3$ and niobium oxide. The dispersion of $Al_2O_3$ in niobium oxide may be attributable to the prevention of the formation of the porous oxide layer. The sulfidation rates of the present ternary alloys arc higher than those of the sputter-deposited Nb-AI binary alloys, but still several orders of magnitude lower than those of conventional high temperature alloys. Two-layered sulfide scales are formed, consisting of an outer $Al_2S_3$ layer containing chromium and an inner layer composed of $NbS_2$ and a small amount of $Cr_2S_3$. The presence of $Cr_2S_3$ in the inner protective $NbS_2$ layer may be attributed to the increase in the sulfidation rates.

• 인간행동과 음악연구
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• 제9권2호
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• pp.19-34
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• 2012

본 연구는 판소리의 치료적 요소에 대해 연구하기 위해 비국악인이 판소리를 감상하는 과정에서 경험하게 되는 요소들을 알아보는데 목적이 있다. 본 연구에서는 5명의 국악을 전공하지 않은 연구 참여자가 판소리를 듣는 동안에 경험하는 것을 심층 면접을 통해 자료로 수집하였고 이를 변형된(modified) 근거 이론 방법으로 분석하였다. 연구결과, 판소리를 감상하는 과정에서 판소리 창자의 창법과 목소리의 음색, 판소리 사설, 고수의 북소리, 고수의 역할 요소는 감상자로 하여금 다양한 차원의 정서, 신체 반응을 경험하고 자신이 경험한 정서와 연관된 사고를 유발하였다. 이는 개인의 내적 문제와 연관되어 자신이 평소에 알지 못했던 내면의 문제를 인식하게 하고, 내 안의 감정과 만나도록 중재되었다. 그리고 감상자가 경험한 개인의 정서와 인식은 또 다른 차원 반응을 유발하여 감상자는 판소리의 요소들을 통해 자신의 부정적 감정을 해결하는 근원을 찾고 내 안의 감정을 정리하는 과정을 경험하였다.

• Transactions on Electrical and Electronic Materials
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• 제18권4호
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• pp.181-184
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• 2017

Multilayer ceramics in which piezoelectric layers of $0.90Pb(Zr_{0.48}Ti_{0.52})O_3-0.05Pb(Mn_{1/3}Sb_{2/3})O_3-0.05Pb(Zn_{1/3}Nb_{2/3})O_3$ (0.90PZT-0.05PMS-0.05PZN) stack alternately with silver electrode layers were prepared by an advanced low-temperature co-fired ceramic (LTCC) method. The electrical properties and bonding strength of the multilayers were associated with the interface morphologies between the piezoelectric and silver-electrode layers. Usually, the inner silver electrodes are fabricated by sintering silver paste in multi-layer stacks. To improve the interface bonding strength, piezoelectric powders of 0.90PZT-0.05PMS-0.05PZN with an average particle size of $23{\mu}m$ were added to silver paste to form a gradient interface. SEM observation indicated clear interfaces in multilayer ceramics without powder addition. With the increase of piezoelectric powder addition in the silver paste, gradient interfaces were successfully obtained. The multilayer ceramics with gradient interfaces present greater bonding strength as well as excellent piezoelectric properties for 30~40 wt% of added powder. On the other hand, over addition greatly increased the resistance of the inner silver electrodes, leading to a piezoelectric behavior like that of bulk ceramics in multilayers.

• Steel and Composite Structures
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• 제33권1호
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• pp.111-122
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• 2019

This paper presents an experimental work on the post-fire behavior of two kinds of innovative composite stub columns under eccentric compression. The partially precast steel reinforced concrete (PPSRC) column is composed of a precast outer-part cast using steel fiber reinforced reactive powder concrete (RPC) and a cast-in-place inner-part cast using conventional concrete. Based on the PPSRC column, the hollow precast steel reinforced concrete (HPSRC) column has a hollow column core. With the aim to investigate the post-fire performance of these composite columns, six stub column specimens, including three HPSRC stub columns and three PPSRC stub columns, were exposed to the ISO834 standard fire. Then, the cooling specimens and a control specimen unexposed to fire were eccentrically loaded to explore the residual capacity. The test parameters include the section shape, concrete strength of inner-part, eccentricity ratio and heating time. The test results indicated that the precast RPC shell could effectively confine the steel shape and longitudinal reinforcements after fire, and the PPSRC stub columns experienced lower core temperature in fire and exhibited higher post-fire residual strength as compared with the HPSRC stub columns due to the insulating effect of core concrete. The residual capacity increased with the increasing of inner concrete strength and with the decreasing of heating time and load eccentricity. Based on the test results, a FEA model was established to simulate the temperature field of test specimens, and the predicted results agreed well with the test results.

• 공업화학
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• 제4권1호
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• pp.196-203
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• 1993

Glycerin monostearate, polyoxyethylene(100) monostearate, polyoxyethylene(20) sorbitan monostearate를 혼합한 유화제를 분산상인 liquid paraffin, beeswax 혼합물에 용해한 후 연속상인 propylene glycol 수용액을 첨가하는 방법인 agent-in-oil법을 적용한 반전유화법에 의해 O/W 에멀젼을 제조하였고, 제조과정에서 나타나는 상거동 및 점성거동을 관찰하였다. 연속상을 주가함에 따라 액정 영역과 백타겔 영역이 존재하는 유화제 조성(HLB 10.1~12.3)에서만 미세하고 균일한 에멀젼이 형성되었으며, 유상${\rightarrow}$액정상${\rightarrow}$겔상${\rightarrow}$O/W 에멀젼으로 상변화가 일어남을 알 수 있었다. 제조된 에멀젼의 전단속도에 따른 전단응력곡선으로부터 항복치가 존재함에 따라 에멀젼 입자간의 내부구조가 형성됨을 알 수 있었고, 전단력에 의한 내부구조의 파괴가 겉보기상으로는 완전히 비가역적으로 진행되며, 구조 파괴의 척도인 hysteresis loop의 면적은 유화제의 HLB값이 작을수록 큰 것을 알 수 있었다. 시간에 따른 전단응력 변화곡선에서소성점성도의 시간의존성이 큰 것을 확인하였고, 시간유동화현상에 따른 완화시간(${\lambda}$)으로부터 HLB값이 작을수록 상대적 안정성이 큼을 알 수 있었으며, homomixer로 제조한 에멀젼에 비해 반전유화법에 의해 제조한 에멀젼이 더 안정함을 알 수 있었다.

• 한국산학기술학회논문지
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• 제22권2호
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• pp.587-592
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• 2021

본 연구의 목적은 예술심리상담사의 감정노동과 삶의 만족도와의 관계에서 일터영성의 매개효과를 파악하는데 있다. 연구대상은 속초시 예술심리상담사 196명을 대상으로 실시하였다. 분석방법은 SPSS 프로그램을 사용하여 빈도분석, 신뢰도분석, 상관관계분석, 변수 간의 인과관계 및 매개효과 검증에 대한 회귀분석을 실시하였다. 연구결과 첫째, 예술심리상담사의 감정노동과 삶의 전반적 만족도와의 관계에서 감정노동의 하위요인인 표면행동, 내면행동 요인 모두 삶의 전반적 만족도와의 관계에서 일터영성은 모두 부분 매개효과가 있는 것으로 확인되었다. 둘째, 예술심리상담사의 감정노동과 삶의 주관적 만족도와의 관계에서 감정노동의 하위요인인 내면행동 요인만 삶의 주관적 만족도와의 관계에서 일터영성은 부분 매개효과가 있는 것으로 확인되었다. 이는 예술심리상담사의 감정노동과 삶의 만족도와의 관계에서 일터영성은 매개역할을 하는 것을 의미하는 것이다. 본 연구의 시사점은 예술심리상담사의 삶의 만족도 증진을 위한 방안 마련의 기초자료가 될 것으로 사료된다.

• 한국콘텐츠학회논문지
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• 제21권2호
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• pp.330-342
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• 2021

본 연구는 사회복지시설에 근무하는 사회복지사의 감정노동과 직무성과의 관계에서 상사와 동료지지의 매개효과를 규명하는 것을 목적으로 설정하였다. 연구대상은 수도권 소재 사회복지시설에 근무하는 사회복지사 445명을 선정하였다. 수집한 자료는 SPSS V22.0을 사용하여 분석한 결과는 다음과 같다. 첫째, 사회복지사의 감정노동에서 표면행동은 직무성과에 부적 영향, 내면행동은 정적인 영향을 직무성과에 미치는 것으로 나타났다. 둘째, 사회복지사의 감정노동에서 표면행동은 상사와 동료지지에 정적 영향, 내면행동은 부적인 영향을 상사와 동료지지에 미치는 것으로 나타났다. 셋째, 사회복지사의 상사와 동료지지가 직무성과에 정적인 영향을 미치는 것으로 나타났다. 넷째, 사회복지사의 표면행동과 직무성과의 관계에서 상사와 동료지지는 부적인 매개 영향을 미치며, 내면행동과 직무성과의 관계에서 상사와 동료지지는 매개 영향을 미치지 않는 것을 밝혔다.

• Journal of Welding and Joining
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• 제24권2호
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• pp.71-78
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• 2006

It has been reported that good quality weld beads are not easily obtained during the $CO_2$ CW laser welding of primer coated plate. However, by introducing a small gap clearance in the lap position, the zinc vapor can escape through it and sound weld beads can be acquired. Therefore, this study examines for keyhole behavior by observing the laser-induced plasma and investigates the relation between keyhole behavior and formation of weld defect. Laser-induced plasma has accompanied with the vaporizing pressure of zinc ejecting from keyhole to surface of primer coated plate. This dynamic behavior of plasma was very unstable and this instability was closely related to the unstable motion of keyhole during laser welding. As a result of observing the composition of porosity, much of Zn element was found from inner surface of porosity. But Zn was not found from the dimple structure fractured at the weld metal. By analyzing of vaporizing element in laser welding, a component ratio of Zn was decreased by introducing a small gap clearance. Therefore we can prove that the major cause of porosity is the vaporization of primer in lap position. Mechanism of porosity-formation is that the primer vaporized from the lap position accelerates dynamic behavior of the key hole and the bubble separated from the key hole is trapped in the solidification boundary and romaines as porosity.

• 한국농공학회지
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• 제42권5호
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• pp.151-159
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• 2000

Dynamic loading of structures often causes excursions of stresses will into the inelastic range and the influence of geometry changes on the response is also significant in may cases. In general , the shell structures designed according to quasi-Static analysis may collapse under condition of dynamic loading. Therefore, for a more realistic prediction on the lad carrying capacity of these shell. both material and geometric nonlinear effects should be considered. In this study , the material nonlinearity effect on the dynamic response is formulated by the elasto-viscoplastic model highly corresponding to the real behavior of the material. Also, the geometrically nonlinear behavior is taken into account using a Total Lagrangian formulation. the reinforcing bars are modeled by the equivalent steel layer at the location of reinforcements, and Von Mises yield criteria is adopted for the steel layer behavior. Also, Drucker-Prager yield criteria is applied for the behavior of concrete. the shape imperfection of dome is assumed as 'dimple type' which can be expressed Wd1=Wd0(1-(r-a)m)n while the shape imperfection of wall is assumed as sinusoidal curve which is Wwi =Wwo sin(n $\pi$y/l). In numerical test, three cases of shape imperfection of 0.0 -5.0cm(opposite direction to loading ; inner shape imperfection)and 5cm (direction to loading : outward shape imperfection) and thickness of steel layer determined by steel ratio of 0,3, and 5% were analyzed. The effect of shape imperfection and steel ratio and behavior characteristics of perfect shape shell and imperfect shape shell are identified through analysis of above mentioned numerical test. Dynamic behaviors of dome and wall according toe combination of shape imperfection and steel ratio are also discussed in this paper.

• Steel and Composite Structures
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• 제30권2호
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• pp.81-96
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• 2019

The behavior of a new Three-Tube Buckling-Restrained Brace (TTBRB) with circumference pre-stress (${\sigma}_{{\theta},pre}$) in core tube are investigated through a verified finite element model. The TTBRB is composed of one core tube and two restraining tubes. The core tube is in the middle to provide the axial stiffness, to carry the axial load and to dissipate the earthquake energy. The two restraining tubes are at inside and outside of the core tube, respectively, to restrain the global and local buckling of the core tube. Based on the yield criteria of fringe fiber, a design method for restraining tubes is proposed. The applicability of the proposed design equations are verified by TTBRBs with different radius-thickness ratios, with different gap widths between core tube and restraining tubs, and with different levels of ${\sigma}_{{\theta},pre}$. The outer and inner tubes will restrain the deformation of the core tube in radius direction, which causes circumference stress (${\sigma}_{\theta}$) in the core tube. Together with the ${\sigma}_{{\theta},pre}$ in the core tube that is applied through interference fit of the three tubes, the yield strength of the core tube in the axial direction is improved from 160 MPa to 235 MPa. Effects of gap width between the core tube and restraining tubes, and ${\sigma}_{{\theta},pre}$ on hysteretic behavior of TTBRBs are presented. Analysis results showed that the gap width and the ${\sigma}_{{\theta},pre}$ can significantly affect the hysteretic behavior of a TTBRB.