• 대한수학회논문집
• /
• 제28권2호
• /
• pp.269-283
• /
• 2013

In this paper, we investigate a stability of the functional equation $$\sum^3_{i=0}_3C_i(-1)^{3-i}f(ix+y)=0$$ by using the fixed point theory in the sense of L. C$\breve{a}$dariu and V. Radu.

• 한국수소및신에너지학회논문집
• /
• 제27권3호
• /
• pp.283-289
• /
• 2016

In this study, electrochemical characterizations of PdCu/C catalysts that are synthesized by modified polyol method are investigated. Most of all, amount of ethylene glycol (EG) that is used as main component for catalyst synthesis is mainly modulated to optimize synthetic condition of the PdCu/C catalyst, For evaluations about catalytic activity and performance of direct formic acid fuel cell (DFAFC), half cell and full cell tests are implemented. As a result, when amount of EG is 4M, catalytic activities of the PdCu/C catalyst such as peak current of formic acid oxidation and active surface area are best, while maximum power density of DFAFC using the optimized PdCu/C catalyst is better than that using commercial Pd/C (30 wt%) by 6%. Based on that, PdCu/C catalyst synthesized by modified polyol method plays a critical role in improving (i) catalytic activity for formic acid oxidation and (ii) DFAFC performance by employing as anodic catalyst.

• Ocean and Polar Research
• /
• 제31권4호
• /
• pp.283-296
• /
• 2009

Oceanographic survey data were analyzed to understand the characteristics of a warm eddy observed in the Ulleung Basin in July 2005. The temperature distribution at 200 db and vertical sections provided evidence of the warm eddy in the Ulleung Basin (UWE05). Based on the 5$^{\circ}C$ isothermal line on 200 db temperature, the major axis was 160 km from southwest to northeast, and the minor axis was 80 km from southeast to northwest. The homogeneous layer in the thermocline of UWE05 had mean values of 10.40$^{\circ}C$ potential temperature, 34.35 psu salinity, and 26.37 kg/m$^3$ potential density (${\sigma}_{\theta}$) and provided evidence that UWE05 also existed during the winter of 2004-2005. A warm streamer initially flowed along the circumference of UWE05 and mixed with the upper central water. Two northward current cores were found on the western side of the measured current section at the central latitude of UWE05. One was the East Korean Warm Current (EKWC) and the other was the main stream of the western part of UWE05. Geostrophic transport of the upper layer (from the surface to the isopycnal surface of 26.9 ${\sigma}_{\theta}$) was approximately 2.5 Sv in the eastern side of UWE05. However, the measured transport was twice as large as the geostrophic transport. Mass conservation of geostrophic transport was well satisfied in the upper layer. The direct current measurements and geostrophic transport analysis showed that the EKWC meandered around UWE05.

• 한국표면공학회지
• /
• 제46권6호
• /
• pp.283-289
• /
• 2013

The experimental study for the temperature uniformity on the wafer using liquid-vapor phase heat transfer mechanism is performed. For the experiment, the heater plate which is consist of stainless steel container, working fluid and electrical heater is designed, manufactured and tested at the range of 600 to $850^{\circ}C$. The results showed that the phase change type heater plate was much more uniform and stable temperature on the heater plate surface and wafer than the uniform heat flux type heater plate at the atmospheric condition. Also, the results of 300 mm outer diameter of heater plate showed that the same temperature uniformity compared with 230 mm.

• Tribology and Lubricants
• /
• 제26권5호
• /
• pp.283-290
• /
• 2010

In this study, the stiffness and damping coefficients of herringbone grooved air journal bearings are studied. A generalized coordinate transformation method to handle the complex geometry of incompressible fluid bearing is modified for compressible fluid. The modified equations are discretized by the base of finite difference method. A new computer program using Visual C++ language is developed. The load carrying capacity and stiffness and damping coefficients are calculated according to the design parameters like groove depth or the number of grooves and compared to that of plain air journal bearings.

• Korean Chemical Engineering Research
• /
• 제57권2호
• /
• pp.283-288
• /
• 2019

Catalytic removal of sulfur compounds from heavy naphtha (HN) was investigated using a combination of an oxidation process using hydrogen peroxide and an adsorption process using granulated activated carbon (GAC) and white eggshell (WES). This study investigated the impact of changing several operating parameters on the desulfurization efficiency. Specifically, the volume ratio of $H_2O_2$ to HN (0.01~0.05), agitation speed ($U_{speed}$) of the water bath shaker ($100-500{\pm}1rpm$), pH of sulfur solution (1~5), amount of adsorbent (0.1~2.5 g), desulfurization temperature ($25{\sim}85{\pm}1^{\circ}C$) and contact time (10~180 minutes) were examined. The results indicate that the desulfurization efficiency resulting from catalytic and adsorption processes of GAC is better than that of WES for oxidation and removing sulfur compounds from HN due to its high surface area. The desulfurization efficiency depends strongly on all investigated operating parameters. The maximum removal efficiency of GAC and WES achieved by this study was 86 and 65, respectively.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
• /
• pp.283-285
• /
• 2002

The paper describes a study of selection of existing a.c. Transmission facilities converted fur use with d.c. system. In order to increasing the power transfer capability of existing a.c. transmission facilities, d.c. is one of good alternatives. Some advantages and disadvantages of this method are discussed, and the selection method of existing transmission facilities for use with d.c. considering economics and stability is presented in this paper.

• 소성∙가공
• /
• 제19권5호
• /
• pp.283-289
• /
• 2010

Extrusion process in the bulk material for fabrication of miniature helical gears has problems such as a high forming load and short tool life because the cross-section is complex and asymmetry. To overcome these problems, in this study, miniature helical gears were fabricated by Zn-22Al powder hot extrusion. The included die angle for minimum extrusion load and improving die filling was determined by FE-simulation. The Zn-22Al spheroidal powder produced by gasatomization were compacted and sintered for extrusion experiment. The dimension of helical-gear is 0.3mm in module, 3.35mm in pitch diameter, $15^{\circ}$ in helix angle and the number of teeth is 12. All of the extrusion experiments were performed with internal helical gear die which was machined by precision electric discharge machining using the electrode. The experiment was conducted at $190^{\circ}C$ to $310^{\circ}C$ to obtain extrusive and mechanical properties. The extruded helical gears were analyzed through extrusion load, Vickers hardness and SEM images for each extrusion temperature. The powder hot extrusion process was successfully applied to fabricate a miniature helical gear.

• 한국융합학회논문지
• /
• 제8권6호
• /
• pp.283-289
• /
• 2017

이 연구는 댄스바이럴 융합 광고에서 댄스가 소비자에게 미치는 영향에 대해 살펴보고자 하는데 목적이 있다. 연구방법은 바이럴과 댄스, 그리고 안무요소의 이론적 배경을 통해 살펴보고자 하였다. 댄스바이럴 영상은 다양한 계층의 소비자들에게 어필하고 있는 현실이다. 특히 2015년 출시된 동아오츠카의 <오로나민C> 광고는 출시된 해 큰 성과를 거두었으며, 중독성 있는 CM송과 댄스로 광고상을 수상한 바 있다. 이에 분석대상으로 <오로나민C> 2015년에서 2017년도 광고를 선택하였다. <오로나민C> 광고 분석결과는 댄스코믹양식의 특징인 간단하고 반복적인 상황연출로 이루어졌으며, 동작은 간결하고 비슷한 유사성과 반복성으로 통일성을 유지하였다. 공간 이동은 거의 이루어지지 않았고, 안무대형은 일렬대형이 주류를 이루었으며, 군중이 모인 경우, 원과 V구도 대형이 나타났다. 공간 구성은 1인칭 시점이 주를 이루었다. 댄스바이럴 <오로나민C> 광고에서 댄스는 전문가적인 댄스보다는 단순하고 쉬운 동작들로 구성된 간결하고 반복적인 요소가 어필하는 것으로 나타났다. 이에 댄스바이럴에서 댄스는 일반인들이 쉽게 따라할 수 있는 동작들과 등장인물 수가 적게 나타날 때 파급효과가 큰 것으로 분석되었다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제40회 동계학술대회 초록집
• /
• pp.283-283
• /
• 2011

The n-doping effect by doping metal carbonate into an electron-injecting organic layer can improve the device performance by the balanced carrier injection because an electron ohmic contact between cathode and an electron-transporting layer, for example, a high current density, a high efficiency, a high luminance, and a low power consumption. In the study, first, we investigated an electron-ohmic property of electron-only device, which has a ITO/$Rb_2CO_3$-doped $C_{60}$/Al structure. Second, we examined the I-V-L characteristics of all-ohmic OLEDs, which are glass/ITO/$MoO_x$-doped NPB (25%, 5 nm)/NPB (63 nm)/$Alq_3$ (32 nm)/$Rb_2CO_3$-doped $C_{60}$(y%, 10 nm)/Al. The $MoO_x$doped NPB and $Rb_2CO_3$-doped fullerene layer were used as the hole-ohmic contact and electron-ohmic contact layer in all-ohmic OLEDs, respectively, Third, the electronic structure of the $Rb_2CO_3$-doped $C_{60}$-doped interfaces were investigated by analyzing photoemission properties, such as x-ray photoemission spectroscopy (XPS), Ultraviolet Photoemission spectroscopy (UPS), and Near-edge x-ray absorption fine structure (NEXAFS) spectroscopy, as a doping concentration at the interfaces of $Rb_2CO_3$-doped fullerene are changed. Finally, the correlation between the device performance in all ohmic devices and the interfacial property of the $Rb_2CO_3$-doped $C_{60}$ thin film was discussed with an energy band diagram.