• 한국정밀공학회지
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• 제17권10호
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• pp.192-199
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• 2000

The design of multi-stage gear drives is a time-consuming process because it includes more complicated problems, which are not considered in the design of single-stage gear drives. The designer has no determine the number of reduction stages and the gear ratios of each reduction stage. In addition, the design problems include not only dimensional design but also configuration design of gear drive elements. There is no definite rule or principle for these types of design problems. Thus the design practices largely depend on the sense and the experiences of the designer, and consequently result in undesirable design solution. A new and generalized design algorithm has been proposed to support the designer at the preliminary phase of the design of multi-stage gear drives. The proposed design algorithm automates the design process by integrating the dimensional design and the configuration design process. The algorithm consists of four steps. In the first step, the user determines the number of reduction stages. In the second step, gear ratios of every stage are chosen using the random search method. The values of the basic design parameters of a gear are chose in the third step by using the generate and test method. Then the values of the dimensions, such as pitch diameter, outer diameter and face width, are calculated for the configuration design in the next step. The strength and durability of each gear is guaranteed by the bending strength and the pitting resistance rating practices by using AGMA rating formulas. In the final step, the configuration design is carried out using simulated annealing algorithm. The positions of gears and shafts are determined to minimize the geometrical volume (size) of a gearbox while avoiding interferences between them. These steps are carried out iteratively until a desirable solution is acquired. The proposed design algorithm is applied to the preliminary design of four-stage gear drives in order to validate the availability. The design solution has considerably good results in both aspects of the dimensional and the configuration design.

• 원예과학기술지
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• 제18권4호
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• pp.513-517
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• 2000

우리나라 난 재배 농가에서 많이 재배하고 있는 호접란 대만 수입묘의 바이러스 감염 정도를 검정하기 위하여 플라스크묘 상태의 실생 번식 식물체를 공시하여 역전사 중합효소 연쇄반응(RT-PCR) 기술에 의해 CymMV와 ORSV의 감염 여부를 검정하였다. 호접란 식물체의 잎에서 조즙액을 추출하여 RT-PCR을 위한 total RNA로 사용하였다. $42^{\circ}C$에서 45분간 반응시켜 cDNA를 합성하였으며, $96^{\circ}C$에서 2분간 template를 예비 변성시킨 후, $96^{\circ}C$에서 30초간 template 변성, $60^{\circ}C$에서 30초간 primer 부착 및 $72^{\circ}C$에서 1분간 DNA 합성을 1cycle로 하여 총 36cycle을 반응시키고, $72^{\circ}C$에서 10분간 안정화하는 조건으로 one-step RT-PCR을 수행하였다. 바이러스 검정 결과 정도의 차이는 있으나, 40개 시료 모두 CymMV에 감염되어 있었으며, ORSV에 감염된 식물체는 없었다.

• 열처리공학회지
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• 제19권5호
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• pp.249-256
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• 2006

Structural studies have been performed on precipitation hardening found in $L1_2$ ordered ${\gamma}^{\prime}-Ni_3(Al,Ti)$ alloys using transmission electron microscopy. A uniform solid solution of ${\gamma}^{\prime}-L1_2$ ordered phase supersaturated with Ni can be obtained by solution annealing in a suitable temperature range. The ${\gamma}^{\prime}$ phase hardens appreciably by the fine precipitation of disordered ${\gamma}$. The shape of ${\gamma}$ precipitates formed during aging is initially spherical or round-cubic and grow into platelets as aging proceeds. High resolution electron microscopy revealed that the ${\gamma}$ precipitates are perfectly coherent with the matrix ${\gamma}^{\prime}$ as long as the ${\gamma}$-precipitates are plates. The loss of coherency initiates by the introduction of dislocations at the ${\gamma}/{\gamma}^{\prime}$ interface followed by the step formation at the dislocations. The ${\gamma}$ precipitates become globular after the loss of coherency. The strength of ${\gamma}^{\prime}-Ni_3(Al,Ti)$ increases over the temperature range of experiment by the precipitation of fine ${\gamma}$ particles. The peak temperature where a maximum strength was obtained shifted to higher temperature.

• 한국전기전자재료학회논문지
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• 제25권5호
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• pp.398-402
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• 2012

Synthesis of $Li_2MnSiO_4$ was attempted by the conventional solid-state reaction method, and the phase formation behavior according to the change of the calcination condition was investigated. When the mixture of the three source materials, $Li_2O$, MnO and $SiO_2$ powders, were used for calcination in air, it was difficult to develop the $Li_2MnSiO_4$ phase because the oxidation number of $Mn^{2+}$ could not be maintained. Therefore, two-step calcination was applied: $Li_2SiO_3$ was made from $Li_2O$ and $SiO_2$ at the first step, and $Li_2MnSiO_4$ was synthesized from $Li_2SiO_3$ and MnO at the second step. It was easy to make $Li_2MnSiO_3$ from $Li_2O$ and $SiO_2$. $Li_2MnSiO_4$ single phase was developed by the calcination at $900^{\circ}C$ for 24 hr in Ar atmosphere as the oxidation of $Mn^{2+}$ was prevented. However, the $Li_2MnSiO_4$ was ${\gamma}-Li_2MnSiO_4$, one of the polymorph of $Li_2MnSiO_4$, which could not be used as the cathode materials in Li-ion batteries. By applying the additional low temperature annealing at $400^{\circ}C$, the single phase ${\beta}-Li_2MnSiO_4$ powder was synthesized successfully through the phase transition from ${\gamma}$ to ${\beta}$ phase.

• 한국전기전자재료학회논문지
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• 제31권2호
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• pp.117-121
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• 2018

Perovskite solar cells have received increasing attention in recent years because of their outstanding power conversion efficiency (exceeding 22%). However, they typically contain toxic Pb, which is a limiting factor for industrialization. We focused on preparing Pb-free perovskite films of Ag-Bi-I trivalent compounds. Perovskite thin films with improved optical properties were obtained by applying an anti-solvent (toluene) washing technique during the spin coating of perovskites. In addition, the surface condition of the perovskite film was optimized using a multi-step thermal annealing treatment. Using the optimized process parameters, $AgBi_2I_7$ perovskite films with good absorption and improved planar surface topography (root mean square roughness decreased from 80 to 26 nm) were obtained. This study is expected to open up new possibilities for the development of high performance $AgBi_2I_7$ perovskite solar cells for applications in Pb-free energy conversion devices.

• 전자공학회논문지A
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• 제33A권6호
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• pp.127-135
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• 1996

To increase the sensitivity and the selectivity of the sensors to TMA gas, the composition ratio and the growth conditions of the ZnO films are studied. Annealing of the ZnO films in the various time ranges and temperatures in the oxygen is carried out to enhance the stbility of the electrical resistance. Pt/Ti heater deposited on backside of the substrates in used to control the operating temperature of th esensor. The ZnO thin film sensors doped to 4.0 wt% $Al_{2}$O$_{3}$ 1.0wt.% TiO$_{2}$ and 0.2wt.% V$_{2}$O$_{5}$ exhibited a high sensitivity and an excellent selectivity for TMA gas. The sensors made with the thin films annealed at 700$^{\circ}$C for 60 minutes in the oxygen atmosphere had a good stability and linearity. The heater deposited in the ratio of 1 to 1 (Pt:Ti) had a good heating properties. The sensors fabricated using above conditions showed a good response to the actual gases of a mackerel at a step of deterioration after death.

• 자원리싸이클링
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• 제9권2호
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• pp.3-10
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• 2000

알루미늄 폐캔은 중요한 재활용 자원으로서 알루미늄 캔용 원소재 판재는 물론 알루미늄의 국내소요량을 전량 수입에 의존하고 있는 우리나라로서는 활용 가능한 알루미늄폐캔의 재활용율을 높여야 하는 것은 외화절약과 환경보호 측면에서 대단히 중요하다. 사용한 알루미늄 캔을 다시 캔으로 재활용 하는 단계는 폐캔의 수집, 파쇄, 선별, 도료제거, 용해 및 2차지금을 제조하는 단계와 이 2차지금을 이용하여 열처리, 열간 및 냉간압연, 중간소둔처리 등을 거쳐 다시 캔을 성형하는 2단계로 나눌수 있다. 본 자료에서는 이러한 알루미늄 캔의 재활용 기술에 대한 우리나라와 선진국들의 현황과 전망을 소개하였다.

• 한국전기전자재료학회논문지
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• 제14권5호
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• pp.370-375
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• 2001

PZT thin films (3500${\AA}$) ahve been prepared onto Pt/Ti/corning glass (1737) substrates with a RF magnetron sputtering system using Pb$\sub$1.50/(Zr$\sub$0.52/,Ti$\sub$0.48)O$_3$ ceramic target. We used two-step annealing techniques, PZT thin films were grown at a 300$^{\circ}C$ substrate temperature and then subjected to an RTA treatment. In case of 500$^{\circ}C$ RTA temperature show pyrochlore phase. The formation of Perovskite phase started above 600$^{\circ}C$ and PZT thin films generated (101) preferred orientation. As the RTA time and temperature increased, crystallization of PZT films were enhanced. The PZT capacitors fabricated at 650$^{\circ}C$ for 10 minutes RTA treatment showed remanent polarization 30 ${\mu}$C/$\textrm{cm}^2$, saturation polarization 42${\mu}$C/$\textrm{cm}^2$, coercive field 110kV/cm, leakage current density 2.83x10$\^$-7/A/$\textrm{cm}^2$, remanent polarization were decreased by 30% after 10$\^$9/ cycles.

• 한국전기전자재료학회논문지
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• 제22권1호
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• pp.41-46
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• 2009

The low dielectric SiOCH films were deposited on p-type Si(100) substrates through the dissociation of BTMSM $(((CH_3)_3Si)_2CH_2)$ precursors with oxygen gas by using PECVD method. BTMSM precursor was introduced with the flow rates from 42 to 60 sccm by 2 sccm step into reaction chamber but with the constant flow rate of 60 sccm $O_2$. SiOCH thin films were annealed at $450^{\circ}C$ for 30 minutes. The electrical property of SiOCH thin films was studied by MIS, Al/SiOCH/p-Si(100), structure. Annealed samples showed large reduction of the maximum capacitance yielding low dielectric constant owing to reductions of surface charge density. After exposure at room temperature and atmospheric pressure, dielectric constant of SiOCH films was totally increased. However, annealed SiOCH thin films were more stable than as-deposited SiOCH thin films for natural oxidation.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
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• pp.230-234
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• 2009

It is significant technique to increase competitiveness that solar cells have a high energy conversion efficiency and cost effectiveness. When making high efficiency crystalline Si solar cells, evaporated Ti/Pd/Ag contact system is widely used in order to reduce the electrical resistance of the contact fingers. However, the evaporation process is no applicable to mass production because high vacuum is needed. Furthermore, those metals are too expensive to be applied for terrestrial applications. Ni/Cu/Ag contact system of silicon solar cells offers a relatively inexpensive method of making electrical contact. Ni silicide formation is one of the indispensable techniques for Ni/Cu/Ag contact sytem. Ni was electroless plated on the front grid pattern, After Ni electroless plating, the cells were annealed by RTP(Rapid Thermal Process). Ni silicide(NiSi) has certain advantages over Ti silicide($TiSi_2$), lower temperature anneal, one step anneal, low resistivity, low silicon consumption, low film stress, absence of reaction between the annealing ambient. Ni/Cu/Ag metallization scheme is an important process in the direction of cost reduction for solar cells of high efficiency. In this article we shall report an investigation of rapid thermal silicidation of nickel on silngle crystalline silicon wafers in the annealing range of $350-390^{\circ}C$. The samples annealed at temperatures from 350 to $390^{\circ}C$ have been analyzed by SEM(Scanning Electron Microscopy).