• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.9 no.1
• /
• pp.106-113
• /
• 2010

The most suitable condition for plasma source ion implantation(PSII) was found based on the study of the characteristics of PSIIed tool and machined surfaces. The depth analysis according to the chemical bonding state of elements and surface component elements through the XPS and SIMS, was conducted to find the improved property of the PSIIed surface. Due to the diffusion of PSII, the nitrogen was found up to a depth of about 150nm according to the supplied voltage and ion implanted time. The deep diffusion by nitrogen caused the surface modification, but the formation of oxide component was found due to the residual gas contamination on the surface. Statistical method of ANOVA was conducted to find the effects of spindle speed and feed rate in interaction for machined surface roughness with PSIIed tools. The surface modification was found largely occurred by the nitrogen implanted surface with 2 hours for 27kV, 35kV and 43kV.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.539-542
• /
• 2001

In SiC semiconductor device processing, it needs high temperature anneal for activation of ion implanted dopants. The macrosteps, 7~8nm in height, are formed on the surface of SiC substrates during activation anneal. We have investigated the effect of thermally-grown SiO$_2$layer on the suppression of macrostep formation during high temperature anneal. The cap oxide layer was found to be efficient for suppression of macrostep formation even though the annealing temperature is as high as the melting point of SiO$_2$. The thin cap oxide layer (10nm) was evaporated during anneal then the macrosteps were formed on SiC substrate. On the other hand the thicker cap oxide layer (50nm) remains until the anneal process ends. In that case, the surface was smoother and the macrosteps were rarely formed. The thermally-grown oxide layer is found to be a good material for the suppression of macrostep formation because of its feasibility of growing and processing. Moreover, we can choose a proper oxide thickness considering the evaporate rate of SiO$_2$at the given temperature.

• Journal of the Korean Chemical Society
• /
• v.28 no.3
• /
• pp.163-169
• /
• 1984

The transport rates of $K^+$ion through CHCl$_3$ liquid membrane containing dibenzo-18-crown-6(DBC) as a carrier molecule have been determined at $25^{\circ}C$. The transport rates depend highly on the ion concentration and on the nature of anion. It is concluded that $K^+$ions are transported in the form of ion-pair. In the case of potassium picrate, however, it is found that the transport proceeds with the formation of the incomplete ion-pair in the concentration less than 1.0 ${\times}10^{-3}$M of picrate, while with the complete formation of ion-pair in the concentration more than 1.0 ${\times}10^{-3}$M of picrate. Seven steps of the transport process are suggested and they can be illustrated in terms of energy barrier model as a function of the position of ionic species in the membrane.

• Journal of Korean Vacuum Science & Technology
• /
• v.6 no.1
• /
• pp.16-21
• /
• 2002

Ti-0 film is a kind of biocompatible surface materials. In this paper, a new method, glow discharge plasma oxidizing, has been used in synthesizing Ti-O gradient films on Ti6A14V substrates. The effects of ion bombardment and process parameters on the structures of titanium oxide layers have been investigated. The results demonstrate that DC glow plasma oxidizing is more efficient in preparation of dense, hard, and high adhesive Ti-O biomedical films on titanium and its alloys. Samples treated by this method show higher hardness values than by others. Especially, in the condition of hollow cathode discharge, the ion bombardment enhances ionization of oxygen, promotes the oxygen permeation and facilitates the formation of the oxide of low valence states of titanium.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.5
• /
• pp.45-51
• /
• 1997

Low temperature activation of dopants which were doped using ion mass doping system in amorphous silicon(a-Si) thin films was investigated. With a 20.angs.-thick Ni film on top of the a-Si thin film, the activation temperature of dopants lowered to 500.deg. C. When the doping was performaed after the deposition of Ni thin film on the a-Si thin films (post-doping), the activation time was shorter than that of dopants mass, the activation time of the dopants doped by pre-doping method increased. It turned NiSi2 formation, while the decrease of activation time was mainly due to the enhancement of the NiSi2 formation by mixing of Ni and a-Si at the interface of Ni and a -Si thin during the ion doping process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.585-586
• /
• 2005

BSCCO thin films were fabricated by an ion beam sputtering method with an ultra-low growth rate, and sticking coefficients of the respective elements are evaluated. The sticking coefficient of Bi element in BSCCO film formation was observed to show a unique temperature dependence; it was almost a constant value of 0.49 below about $730^{\circ}C$ and decreased linearly over about $730^{\circ}C$. In contrast, Sr and Ca, displayed no such remarkable temperature dependence. This behavior of the sticking coefficient was explained consistently on the basis of the evaporation and sublimation processes of Bi2O3. It is considered that the liquid phase of the bismuth oxide plays an important role in the Bi 2212 phase formation in the co-deposition process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.824-827
• /
• 2000

Fabrication of InP-based photonic devices by dry etch Process is important for clear formation of waveguide mesa structure. We have developed more efficient etch process of the inductively coupled plasma (ICP) with low damages and less polymeric deposits for the InP-based photonic devices than the reactive ion etching (RIE) technique. We report the tendency of etch rate variation by the process parameters of the RF power, pressure, gas flow rate, and the gas mixing ratio. The surface roughness of InP-based waveguide structure was more improved by the light wet etching in the mixed solution of H$_2$SO$_4$:H$_2$O (1:1)

• Journal of the Korean Ceramic Society
• /
• v.41 no.12 s.271
• /
• pp.889-892
• /
• 2004

Acicular type aragonite precipitated calcium carbonate was synthesized by carbonation reaction of $Ca(OH)_2$ slurry and $CO_2$ gas. As increasing the initial concentration of $Mg^{2+}$ ion, calcite crystal phase substantially decreased while that of aragonite crystal phase increased. According to XRD and EDS analysis, it was found that the addition of $MgCl_2$ induced the $Mg^{2+}$ ion to substitute in $Ca^{2+}$ ion site of calcite lattice then the unstabled calcite structure be resolved, consequently the growth of calcite structure is interrupted while the growth of aragonite structure is expedited.

• Korean Chemical Engineering Research
• /
• v.55 no.5
• /
• pp.718-722
• /
• 2017

We have investigated the photocatalytic activity for the decomposition of methyl orange on the pure $LaCoO_3$ and metal ion doped $LaCoO_3$ perovskite-typeoxides prepared using microwave process. In the case of pure $LaCoO_3$ and cesium ion doped $LaCoO_3$ catalysts, the formation of the perovskite crystalline phase was confirmed regardless of the preparation method. From the results of UV-Vis DRS, the pure $LaCoO_3$ and cesium ion doped $LaCoO_3$ catalysts have the similar absorption spectrum up to visible region. The chemisorbed oxygen plays an important role on the photocatalytic decomposition of methyl orange and the higher the contents of chemisorbed oxygen, the better performance of photocatalyst.

• School Science Journal
• /
• v.12 no.2
• /
• pp.164-177
• /
• 2018

이 연구의 목적은 원자와 이온 생성 과정의 표상에 대한 중학생들의 이해도를 파악하는 것이다. 이를 위하여 교과서에 제시되어 있는 원자와 이온 생성 과정의 표상을 선정하여 서술형 검사를 구성하였고, 원자와 이온 생성 과정에 대한 이해도를 추가적으로 파악하기 위한 선다형 검사를 개발하였다. 임의로 표집한 서울 시내 중학교 한 곳의 2학년 학생 237명을 대상으로 연구를 진행하였다. 원자의 구성 입자와 이온의 생성 과정을 나타낸 표상에 대한 학생들의 서술 내용을 분석한 결과, 교육과정에 제시된 성취기준과 관련된'원자에는 원자핵과 전자가 있다'와 '원자가 전자를 잃으면 양전하를 띠고, 전자를 얻으면 음전하를 띠게 된다'는 내용이 가장 높은 빈도로 나타났다. 또한 원자의 구성 입자에 대한 표상에 비하여 동적인 표상이 강화된 이온 생성 과정에 대한 표상에서는 현상 자체에 대한 서술보다 과정에 대한 서술 내용이 더 높은 빈도로 나타났다. 한편 학생들은 표상에 나타난 표면적인 정보를 위주로 서술하는 경향을 보였으며, 이로 인해 상황 특수적인 정보를 일반화하는 오류가 나타났다. 서술형 응답과 선다형 응답 내용을 비교한 결과, 선다형 검사에서 올바른 응답을 했더라도 관련 개념을 총체적으로 이해하고 있지 못하고 있는 학생들이 있음을 확인할 수 있었다. 연구 결과를 바탕으로 교육적 시사점을 논의하였다.