• Journal of the Korean Vacuum Society
• /
• v.7 no.s1
• /
• pp.30-36
• /
• 1998

The plasma-spray technique is currently the most frequently used method to produce calcium phosphate coatings. Hydroxyapatite(HAp), one form of calcium phosphate, is preferred by its ability to form a direct bond with living bone, resulting in improvements of implant fixation and faster bone healing. Recently, concerns have been raised regarding the viable use and long-term stability of plasma-spray HAp coatings due to its nature of comparatively thick, porous, and poor bonding strength to metal implants. Thin layers (maximum of few microns) of calcium phosphate were formed by an e-beam evaporation with and without ion bombardments. The Ca/P ration of film was controlled by either using the evaporants having the different ration of Ca/P with addition of CaO, or adjusting the ion beam assist current. The Ca/P ration had great effects on the structure formation after heat treatment and the dissolution bahavior. The calcium phosphate films produced by IBAD exhibited high adhesion strength.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.04b
• /
• pp.5-8
• /
• 2004

전자빔 증착법 (e-beam evaporation)를 이용하여 $TiO_2$ 박막과 $Al_2O_3/TiO_2$ 이중박막을 제조한 후, $800^{\circ}C$ 공기 중에서 열처리하여, 알루미나 층의 유무에 따른 두 박막의 전기전도 특성과 100 ppm CO 가스에 대한 반응 특성을 고찰하였다. 알루미나 층이 증착되지 않은 순수한 $TiO_2$ 박막의 전기 전도도 (in dry air)는 $100^{\circ}C-500^{\circ}C$ 온도범위에서 온도가 증가함에 따라 증가하였으며 알루미나 층이 증착된 $Al_2O_3/TiO_2$ 이중막보다 높은 전도도를 나타내고 있으나, 약 $300^{\circ}C$이상의 온도에서는 $Al_2O_3/TiO_2$ 이중막의 전기 전도도가 급격히 증가하여 $TiO_2$ 박막의 전기전도도 보다 더 높은 값을 나타내었다. 또한 온도에 따른 CO 가스 감도(sensitivity)는 $TiO_2$ 박막의 경우 $400^{\circ}C$까지는 서서히 증가하여 그 이상의 온도에서 급격히 감소하였으나, $Al_2O_3/TiO_2$ 이중막은 $250^{\circ}C$에서 감도가 급격히 증가하여 최대값을 나타내었으며, $350^{\circ}C$에서 감도가 급격히 감소하는 특성을 나타내었다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1999.07a
• /
• pp.100-100
• /
• 1999

가시광선 영역에서 높은 광학적 투과성과 함께 우수한 전기 전도성을 갖는 ITO 박막은 디스플레이 소자나 투명전극재료 등 다양한 분야에서 응용성이 더욱 증대되고 있다. 증착기판으로서 유리를 사용할 때 생기는 활용범위 제한을 극복하고자 최근 유기물 위에 증착이 가능한 저온 증착방법에 대한 연구가 활발히 이루어지고 있다. 그 가운데 이온빔과 같은 energetic한 beam을 이용한 박막의 제조는 기판을 플라즈마 발생지역으로부터 분리시켜 이온빔의 flux 및 에너지, 입사각 등의 자유로운 조절을 통해 상온에서도 우수한 성질의 박막 형성 가능성이 제시되어 왔다. 본 연구에서는 ion beam assisted evaporation방법을 이용하여 ITO 박막을 성장시켰으며, ion-surface interaction 효과가 박막 성장주에 미치는 영향을 이해하기 위하여 먼저 반응성 산소 이온빔에 비 반응성 아르곤 이온빔을 다양하게 변화시켜가며 증착하였으며, 이와 더불어 산소 분위기에서 아르곤 이온빔에 의한 ITO 박막의 특성 변화를 각각 관찰하였다. 증착전 후의 열처리 없이 상온에서 비저항이 ~10-4$\Omega$cm 이하로 낮고 80% 이상의 투과율을 갖는 ITO 박막을 성장시켰다. 실험에서 이용된 e-beam evaporation 물질은 In2O3-SnO2(1-wt%)였으며, 이온빔 source는 산소에 의한 filament의 산화를 막기 위해 filament cathodes type이 아닌 rf(radio-frequency)를 사용하였다. 중요 증착변수인 이온빔의 flux 변화는 산소와 Ar의 flow rate를 MFC로 조절하고 rf power를 변화시켜 얻었으며, 이온빔 에너지는 가속 grid의 가속전압 변화와 ion gun과 기판사이의 거리 조절을 통해 최적화하였다. 이온빔의 에너지와 flux는 Faraday cup으로 측정하였으며, 성박된 박막의 특성은 UV-spectrometer, 4-point probe, Hall measurement. $\alpha$-step, XRD, XPS 등을 이용하여 광학적, 전기적, 구조적 특성을 분석하였다.

• Journal of the Korean Society of Safety
• /
• v.37 no.4
• /
• pp.129-138
• /
• 2022

A new method for injecting cooling water into the Korean research reactor (KRR) in the event of beam tube rupture is proposed in this paper. Moreover, the research evaluates the risk to the reactor core in terms of core damage frequency (CDF). The proposed method maintains the cooling water in the chimney at a certain level in the tank to prevent nuclear fuel damage solely by gravitational coolant feeding from the emergency water supply system (EWSS). This technique does not require sump recirculation operations described in the current procedure for resolving beam tube accidents. The reduction in the risk to the core in the event of beam tube rupture that can be achieved by the proposed change in the cooling water injection design is quantified as follows. 1) The total CDF of the KRR for the proposed design change is approximately 4.17E-06/yr, which is 8.4% lower than the CDF of the current design (4.55E-06/yr). 2) The CDF for beam tube rupture is 7.10E-08/yr, which represents an 84.1% decrease compared with that of the current design (4.49E-07/yr). In addition to this quantitative reduction in risk, the modified cooling water injection design maintains a supply of pure coolant to the EWSS tank. This means that the reactor does not require decontamination after an accident. Thermal hydraulic analysis proves that the water level in the reactor pool does not cause damage to the nuclear fuel cladding after beam tube rupture. This is because the amount of water in the chimney can be regulated by the EWSS function. The EWSS supplies emergency water to the reactor core to compensate for the evaporation of coolant in the core, thus allowing water to cover the fuel assemblies in the reactor core over a sufficient amount of time.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.806-809
• /
• 2003

Ion-induced secondary electron emission coefficient $({\gamma})$. of the patterned MgO thin film with geometrical structures has been measured by ${\gamma}$ - FIB(focused ion beam) system. The patterned MgO thin film with geometrical structures has been formed by the mask (mesh of ${\sim}$ $10{\mu}m^{2})$ under electron beam evaporation method. It is found that the higher ${\gamma}$. has been achieved by the patterned MgO thin film than the normal ones without patterning.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.906-909
• /
• 2006

The secondary electron emission coefficient $({\gamma})$ of the cathode is an important factor for improving the discharge characteristics of AC-PDPs because of its close relationship to discharge voltage. In AC-PDPs, MgO is most widely used as a surface protective layer. In this experimental, we have investigated the electronic structure of the energy band structure of the MgO layer responsible for the high ${\gamma}$. The MgO layers have been deposited by electron beam evaporation method, where the $O_2$ partial pressures have been varied as 0, $5.2{\times}10^{-5}$ torr, $1.0{\times}10^{-4}$ torr, and $4.1{\times}10^{-4}$ torr, in this experiment. It is noted that work function that is energy gap between surface and first defect level of MgO layer has the lowest value for the highest O2 partial pressure of $4.1^{\ast}10^{-4}$ Torr.

• Journal of the Korean Physical Society
• /
• v.73 no.9
• /
• pp.1346-1350
• /
• 2018

An electrode-evaporation technology on both the top and bottom sides of the bare vertical-type single chip separated from the traditional substrate by cooling, was developed for III-nitride vertical-type single chip LEDs with thick GaN epilayer. The post-process of the cooling step was followed by sorting the bare vertical-type single chip LEDs into the holes in a pocket-type shadow mask for deposition of the electrodes at the top and bottom sides of bare vertical-type single chip LEDs without the traditional substrate for electrode evaporation technology for vertical-type single chip LEDs. The variation in size of the hole between the designed shadow mask and the deposited electrodes owing to the use of the designed pocket-type shadow mask is investigated. Furthermore, the electrical and the optical properties of bare vertical-type single chip LEDs deposited with two different shapes of n-type electrodes using the pocket-type shadow mask are investigated to explore the possibility of the e-beam evaporation method.

• Journal of the Korean Ceramic Society
• /
• v.39 no.12
• /
• pp.1171-1176
• /
• 2002

The growth characteristics on the MgO thin films prepared by the e-beam evaporation method have been investigated. We observed the film of preferred orientation and surface morphology with various parameters such as substrate temperature, deposition rate on Si(100) and slide glass respectively. Consequently, it was shown that MgO(111) preferred orientation films can be obtained as the deposition rate was increased on Si(100) substrate. MgO(220) peak was found as the substrate temperature was increased. Whereas, in case of slide glass the orientation is changed from (200) to (111) by substrate temperature. Also we investigated the relationship between the film characteristics and the orientation of MgO thin films.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08b
• /
• pp.1395-1398
• /
• 2007

MgO thin films were deposited by e-beam evaporator using the 2-step method for alternate current plasma display panels (AC-PDPs). Glancing angle deposition (GLAD) method was employed to produce various surface geometry of the thin film; the bottom layer was deposited on a substrate by normal e-beam evaporation method and the top layer was deposited on bottom layer with $85^{\circ}$ by GLAD method. Results show that firing and sustain voltages improved as the sharpness of surface and isolated columnar structures increases, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.11a
• /
• pp.357-360
• /
• 1996

MgO protection layer in ac PDP(plasma display panel) prevents the dielectric layer from ion bombarding in discharge plasma. The MgO layer also has the additional important role in lowering the firing voltage due to a large secondary electron emission coefficient. Until now, the MgO protection layer is mainly prepared by E-beam evaporation. In this study, MgO protection layer is prepared on dielectric layer of ac PDP cell by reactive R.F magnetron sputtering with Mg target under various conditions of oxygen partial pressure. Discharge characteristics of PDP is also studied as a parameter of MgO preparation conditions. The sputtered MgO shows the better discharge characteristics compared with MgO deposited by E-beam evaporator.