• Design & Manufacturing
• /
• 제14권4호
• /
• pp.71-77
• /
• 2020

Various manufacturing technologies, including over-molding and insert-injection molding, are used to produce hybrid plastics and metals. However, there are disadvantages to these technologies, as they require several steps in manufacturing and are limited to what can be reasonably achieved within the complexities of part geometry. This study aims to determine a practical approach for producing metal/plastic hybrid components by combining plastic injection molding and metal die casting to create a new hybrid metal/plastic molding process. The integrated metal/plastic hybrid injection molding process developed in this study uses the proven method of multi-component technology as a basis to combine plastic injection molding with metal die casting into one integrated process. In this study, the electrical conductivity and ampacity were verified to qualify the new process for the production of parts used in electronic devices. The electrical conductivity was measured, contacting both sides of the test sample with constant pressure, and the resistivity was measured using a micro ohmmeter. Also, the specific conductivity was subsequently calculated from the resistivity and contact surface of the conductor path. The ampacity defines the maximum amount of current a conductive path can carry before sustaining immediate or progressive deterioration. The manufactured hybrid multi-components were loaded with increasing currents, while the temperature was recorded with an infrared camera. To compare the measured infrared images, an electro-thermal simulation was conducted using commercial CAE software to predict the maximum temperature of the power loaded parts. Overall, during the injection molding process, it was demonstrated that multifunctional parts can be produced for electric and electronic applications.

• Corrosion Science and Technology
• /
• 제6권3호
• /
• pp.133-139
• /
• 2007

Nickel powder was coated with aluminum nitrate solution to increase the thermal stability of a porous nickel support and control the nickel content in the Pd-Cu-Ni ternary alloyed membrane. Raw nickel powder and alumina coated nickel powder were uniaxialy pressed by home made press with metal cylindrical mold. Though the used nickel powder prepared by pulsed wire evaporation (PWE) method has a good thermal stability, the porous nickel support was too much sintered and the pores of porous nickel support was plugged at high temperature (over $800^{\circ}C$) making it not suitable for the porous support of a palladium based composite membrane. In order to overcome this problem, the nickel powder was coated by alumina and alumina modified porous nickel support resists up to $1000^{\circ}C$ without pore destruction. Furthermore, the compositions of Pd-Cu-Ni ternary alloy membrane prepared by magnetron sputtering and Cu-reflow could be controlled by not only Cu-reflow temperature but also alumina coating amount. SEM analysis and mercury porosimeter analysis evidenced that the alumina coated on the surface of nickel powder interrupted nickel sintering.

• 한국구조물진단유지관리공학회 논문집
• /
• 제18권5호
• /
• pp.116-127
• /
• 2014

대단면 터널 라이닝 콘크리트를 1일에 1cycle로 진행하기 위한 연구를 수행하였다. 터널 내부의 기후특성이 변화하고 콘크리트 타설온도가 낮은 경우에는 수화발현 속도도 지연되어 강도발현에 영향을 미치게 되므로 거푸집의 존치시간이 길어지게 된다. 이를 보완하기 위하여 갱문의 설치와 갱폼의 양쪽에 양생막을 설치한 후, 그 내부에 $28{\pm}2^{\circ}C$의 추가적인 열원을 공급하게 되면 균열관리방안으로 제시한 관리 기준 (4.5MPa) 이상의 조기강도발현을 이루어 낼 수 있었으며, 따라서 거푸집을 재령 14hr 후에 제거할 수가 있었다. 한편, 터널내 자연양생온도인 $10{\pm}1^{\circ}C$ 조건에서는 콘크리트 타설 후 36hr 이상의 양생시간을 확보해야 되는 것으로 분석되었다. 본 연구를 통하여, 초기재령에서의 콘크리트 온도와 강도발현은 양생온도가 크게 작용하고 있음을 재확인 할 수 있었으며, 플라이애쉬가 10% 혼입된 콘크리트라도 일정 시간동안 거푸집의 표면온도를 상승시켜 줄 수 있다면 조기강도발현에는 문제가 되지 않는 것으로 나타났다.

• 농약과학회지
• /
• 제18권4호
• /
• pp.429-433
• /
• 2014

2012년 경상남도 진주시 농산물도매시장에서 구입한 사과에서 분홍빛열매썩음병이 발생하였다. 병징은 사과 과실 표면이 갈색으로 변하면서 약간 함몰되어지고 수침상으로 물러지고 썩으면서 그 위에 분홍빛 곰팡이가 형성되었다. 감자한천배지 위에서 균총의 색깔은 처음 흰색이고 배양기간이 경과됨에 따라 분홍빛의 분생포자가 많이 형성되었다. 균사생육 적온은 $25^{\circ}C$이었다. 분생포자의 모양은 서양배형이며 좌우 지그자그로 부착하며 성숙한 분생포자는 2개의 세포로 되어있다. 크기는 $12-26{\times}8-12{\mu}m$이었다. 분생자경은 균사표면에 직립으로 형성하고, 폭이 $4-5{\mu}m$이고 무색이었다. 위와 같은 결과를 통해 사과에서 발생한 병징과 병원균의 균학적 특징을 기초로 하여 이 병을 Trichothecium roseum (Pers.) Link ex Gray에 의한 사과 분홍빛열매썩음병으로 명명하고자 제안한다.

• 식물병연구
• /
• 제19권3호
• /
• pp.226-228
• /
• 2013

2012년 경상남도 진주시 농산물도매시장에 판매중인 감귤에서 분홍빛열매썩음병이 발생하였다. 병징은 감귤 과실 표면이 수침상으로 물러지고 썩으면서 그 위에 분홍빛 곰팡이가 많이 형성되었다. 균총의 색깔은 처음에 흰색이고 배양기간이 경과됨에 따라 배지 표면에 분홍빛의 분생포자가 많이 형성되었다. 균사생육 적온은 $25^{\circ}C$이었다. 분생포자의 모양은 서양배형이며 좌우 zigzag로 부착하며 성숙한 분생포자는 2세포로 되어 있으며 크기는 $12-26{\times}8-12{\mu}m$이었다. 분생자경은 균사표면에 직립으로 형성하고, 폭이 4-5 ${\mu}m$이고 무색이었다. rDNA의 complete internal transcribed spacer(ITS) 영역의 염기서열을 분석하였고, 분석된 염기서열(613 bp)을 BLASTN 프로그램으로 확인한 결과, Trichothecium roseum와 99%의 상동성을 나타내었다. 이와 같이 감귤에서 발생한 병징과 병원균의 균학적 특징을 기초로 하여 이 병을 Trichothecium roseum(Pers.) Link ex Gray에 의한 감귤 분홍빛열매썩음병으로 명명하고자 제안한다.

• 한국재료학회지
• /
• 제17권1호
• /
• pp.31-36
• /
• 2007

Nanoimprint lithography (NIL) is a new lithographic method that offers a sub-10nm feature size, high throughput, and low cost. One of the most serious problems of NIL is the stiction between mold and resist. The antistiction layer coating is very effective to prevent this stiction and ensure the successful NIL results. In this paper, an antistiction layer was deposited by VSAM (vapor self assembly monolayer) method on silicon samples with FOTS (perfluoroctyltrichlorosilane) as a precursor for making an antistiction layer. A specially designed LPCVD (low pressure chemical vapor deposition) was used for this experiment. All experiments were achieved after removing the humidity. First, the evaporation test of FOTS was performed for checking the evaporation temperature at low pressure. FOTS was evaporated at 5 Tow and $110^{\circ}C$. In order to evaluate the temperature effect on antistiction layer, chamber temperature was changed from 50 to $170^{\circ}C$ with 0.1ml of FOTS for 1 minute. Good hydrophobicity of all samples was shown at about $110^{\circ}$ of contact angle and under $20^{\circ}$ of hysteresis. The surface energies of all samples calculated by Lewis acid/base theory was shown to be about 15mN/m. The deposited thicknesses of all samples measured by ellipsometry were almost 1nm that was similar value of the calculated molecular length. The surface roughness of all samples was not changed after deposition but the friction force showed relatively high values and deviations deposited at under $110^{\circ}$. Also the white circles were founded in LFM images under $110^{\circ}$. High friction forces were guessed based on this irregular deposition. The optimized VSAM process for FOTS was achieved at $170^{\circ}C$, 5 Torr for 1 hour. The hot embossing process with 4 inch Si mold was successfully achieved after VSAM deposition.

• Restorative Dentistry and Endodontics
• /
• 제19권1호
• /
• pp.1-26
• /
• 1994

The purpose of this study was to investigate the dissolution components during corrosion of amalgams and to identify surface corrosion products in the modified Fusayama artificial saliva. Four type of amalgam alloys were used: low copper lathe cut amalgam alloy (Cavex 68), low copper spherical amalgam alloy (Caulk Spherical Alloy), high copper admixed amalgam alloy (Dispersalloy) and high copper single composition amalgam alloy (Tytin). Each amalgam alloy and Hg were triturated according to the manufacturer's direction by means of mechanical amalgamator (Capmaster, S.S.White), and then the triturated mass was inserted into the cylindrical metal mold which was 10mm in diameter and 2.0mm in height and condensed with compression of 150kg/$cm^2$ using oil pressor. The specimens were removed from the mold and stored at room temperature for 7 days and cleansed with distiled water for 30 minutes in an ultrasonic cleaner. The specimens were immersed in the modified Fusayama artificial saliva for the periods of 1 month, 3 months and 6 months. The amounts of Hg, Cu, Sn and Zn dissolved from each amalgam specimen immersed in the artificial saliva for the periods of 1 month, 3 months and 6 months were measured using Inductivity Coupled Plasma Atomic Emission Spectrometry (ICPQ-1000, Shimadzu, Japan) and amount of Ag dissolved from amalgam specimen was measured using Atomic Absorption Spectrophotometry (Atomic Absorption/Flame emission spectrophotometer M-670, Shimadzu, Japan). A surface corrosion products of specimens were analysed using Electron Spectroscopy Chemical Analyser (ESCA PHI-558, PERKIN ELMER, U.S.A.). The secondary image and back scattered image of corroded surface of specimens was observed under the SEM, and the corroded surface of specimens was analysed with the EDX. The following results were obtained. 1. The dissolution amount of Cu was the most in high copper admixed amalgam(Dispersalloy) and the least in high copper single composition amalgam(Tytin). 2. Sn and Zn were dissolved during all the experiment periods, and dissolution amounts were decreased as the time elapsed. 3. Initial surface corrosion products were ZnO and SnO. 4. Corrosion of ${\gamma}$ and ${\gamma}_2$ phase in low copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in low copper spherical amalgam(Caulk Sperical Alloy). 5. Corrosion of ${\gamma}$ and $\eta$' phase in high copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in high copper admixed amalgam(Dispersalloy). 6. Sn-Cl was produced in the subsurface of low copper amalgams and high copper admixed amalgam.

• 한국기계가공학회지
• /
• 제19권6호
• /
• pp.55-60
• /
• 2020

The injection molding technique is a processing method widely used for the production of plastic parts. In this study, the gate position, gate size, packing time, and melt temperature were optimized to minimize both the stress and deformation that occur during the injection molding process of medical suction device components. We used a central composite design and Latin hypercube sampling to acquire the data and adopted the response surface method as an approximation method. The efficiency of the optimization of the injection molding problem was determined by comparing the results of a genetic algorithm, sequential quadratic programming, and a non-dominant classification genetic algorithm.

• 한국산학기술학회논문지
• /
• 제4권3호
• /
• pp.168-171
• /
• 2003

본 연구에서는 일반사출과 MmSH방식 두 가지의 사출성형공정을 이용하여 나노패턴 구조물을 제작하였다. 성형품에 나타난 나노패턴의 전사성은 MmS방식을 이용한 PC 성형품에서 가장 우수했다. 일반사출공정에서 HIPS로 제작된 성형품은 나노패턴의 전사가 잘 형성되었고, PC의 경우 전사가 잘 이루어지지 않았다 연구 결과 수지의 유동성이 좋고, 금형표면 온도가 높을수록 나노패턴의 전사성은 향상됨을 알 수 있었다.

• 한국초전도저온공학회:학술대회논문집
• /
• 한국초전도저온공학회 2001년도 학술대회 논문집
• /
• pp.25-28
• /
• 2001

Bi-2212 HTS tube was fabricated by centrifugal forming process(CFP). As a variation of melt casting process(MCP) or centrifugal casting technique, the centrifugal forming process is a flexible method for manufacturing Bi-2212 bulk tubes and has been optimized to achieve smooth surface and uniform thickness. At this process, the slurry was prepared in the mixing ratio of 10:1 between Bi-2212 powder and binder and initially charged into the rotating mold under the speed of 300~450 rpm Heat-treatment was performed at the temperature ranges of 860 ~ $890^{\circ}C$ in air for partial melting. The HTS tube fabricated by centrifugal forming process at $890^{\circ}C$ under the rotating speed of 450 rpm was highly densified and the plate-like grains with more than 20$\mu$m were well oriented along the rotating axis. The measured Tc and Jc at 10K were around 85K and 3,000A/cm2 respectively.