• Title/Summary/Keyword: 급속 냉각 기술

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A study on the formation of local back surface field using Rapid Thermal Process (Rapid Thermal Process를 이용한 실리콘 태양전지의 국부적 후면 전극 최적화)

  • Bae, Soohyun;Park, Sungeun;Kim, Young Do;Park, Hyomin;Kim, Soo Min;Kim, Seongtak;Kim, Hyunho;Tark, Sung Ju;Kim, Dongwhan
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.121.1-121.1
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    • 2011
  • 현재 상용화되고 있는 단결정 실리콘 태양전지는 알루미늄 페이스트를 이용하여 후면의 전 영역에 전계를 형성한다. 최근에는 고효율을 얻기 위하여 후면에 패시베이션 효과와 장파장에 대한 반사도를 증가 시키는 SiNx막을 증착 후, 국부적으로 전계를 형성하는 국부 후면 전극(Local back surface field)기술이 연구되고 있다. 본 연구에서는 전면만 텍스쳐 된 단결정 실리콘 웨이퍼를 이용하였다. Plasma Enhanced Chemical Vapor Deposition(PECVD)를 이용하여 전,후면에 SiNx를 증착 하였고 후면의 국부적인 전극 패턴 형성을 위하여 SiNx 식각용 페이스트를 사용한 스크린 프린팅 기술을 이용하였다. 스크린 프린팅을 이용하여 패턴이 형성된 후면에 알루미늄을 인쇄 한 후 Rapid Thermal Process(RTP)를 이용하여 소성 공정 조건을 변화시켰다. 소성 조건 동안 형성되는 후면 전계층은 peak 온도와 승온속도, 냉각 속도에 따라 형상이나 특성이 변화하기 때문에 소성 조건을 변화시키며 국부적 후면 전계 형성의 최적화에 관한 연구를 수행하였다. 패이스트를 이용하여 SiNx를 식각 후 광학 현미경(Optical Microscopy)을 사용하여 SiNx의 식각 유무를 살펴보았고, RTP로 형성된 국부 전계층의 형성 두께, 주변 부분의 형상을 살피기 위해 도핑 영역을 혼합수용액으로 식각하여 주사 전자 현미경(SEM)을 이용하여 관찰 하였다. 또한 후면의 특성을 살펴보기 위해 분광 광도계(UV/VIS/NIR Spectrophotometer)를 사용하여 후면 SiNx층의 유무에 따른 반사도를 비교, 측정 하였다.

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Open Pulled Straws, EM Grid, Nylon Loop법에 의한 돼지성숙난자의 유리화동결 비교

  • 안미현;김인덕;석호봉
    • Proceedings of the KSAR Conference
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    • 2003.06a
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    • pp.83-83
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    • 2003
  • 돼지 난자의 유리화 동결 처리 방법 중 난자를 담는 용기(loading vessel)의 재료로 최근에 알려진 것으로 open-pulled straws(OPS)[Vajta등, Mol Reprod Dev, 51:53-58, (1998)], electron microscope grids(EMG) [Martino등,Biol Reprod, 54:1059-1069, (1996)〕, nylon loop system(NLS) [Lane등, Fertil Steril,72: 1073-1078, (1999)] 등이 보고되고 있다. OPS는 1/4cc straws를 열을 가하여 길게 뽑아 내벽을 얇게 함으로써 filing된 난자나 수정란이 액체 질소와 접촉했을 때 유리화가 신속하게 되도록 하는 방법으로 돼지에서는 별로 보고된 것이 없다. EMG는 열전도가 예민한 전자현미경용 copper grid를 이용한 방법으로 최근 국내 기술진의 연구성적을 포함한 몇몇 학자들에 의하여 보고되었고 NLS는 0.5mm직경의 nylon loop를 이용하여 급속 동결한 성적이 보고되었으나, 돼지 난자에 응용 된 것은 없다. 따라서 이와 같은 동결 재료는 사람과 반추류, mouse외에 돼지 난자에 대하여는 전혀 시도되지 않았지만 유리화 동결기술에서 가장 중요한 실험으로 생각된다. 성공적인 유리화 동결을 위해서는 수정란이 냉각의 전도성이 빠르고, 작은 용액을 수정란과 같이 filling해야 하며 모든 동작이 신속 간편해야 하며 융해 방법도 초급속도의 융해가 요구되므로 이에 부합되어야 한다. 연구 목적은 돼지 난자를 유리화 동결/융해 시 동결 재료-straw/glass, copper grid, nylon 3가지에 대한 제작 방법, 난자 loading, 동결 처리, 보관 방법, 융해 방법 등을 난자의 회수, 수정 후 생존율을 비교 조사하여 가장 우수한 방법을 선택할 목적이었다. 수행 내용은 3가지의 재료의 sample을 제작하고 소독한 다음 준비된 돼지 COCs을 40시간동안 IVM한 후 난자를 5~l5개 정도로 선정 하여 준비된 VS 용액에 평형처리 하였다. 각 재료의 용기에 loading 한 후 동결/보관하였고, 융해는 역순으로 평형하여 maturation 배지에 3~4시간 배양한 다음 경검하고 IVF한 후 NCSU-23 배지에 담아 IVC 배양하면서 cell cleavage상태를 확인하였다.

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Changes on the Microstructure of an Al-Cu-Si Ternary Eutectic Alloy with Different Mold Preheating Temperatures (금형 예열온도에 따른 Al-Cu-Si 3원계 공정합금의 미세조직 변화)

  • Oh, Seung-Hwan;Lee, Young-Cheol
    • Journal of Korea Foundry Society
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    • v.42 no.5
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    • pp.273-281
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    • 2022
  • In order to understand the solidification behavior and microstructural evolution of the Al-Cu-Si ternary eutectic alloy system, changes of the microstructure of the Al-Cu-Si ternary eutectic alloy with different cooling rates were investigated. When the mold preheating temperature is 500℃, primary Si and Al2Cu dendrites are observed, with (α-Al+Al2Cu) binary eutectic and needle-shaped Si subsequently observed. In addition, even when the mold preheating temperature is 300℃, primary Si and Al2Cu dendrites can be observed, and both (α-Al+Al2Cu+Si) areas observed and areas not observed earlier appear. When the mold preheating temperature is 150℃, bimodal structures of the binary eutectic (α-Al+Al2Cu) and ternary eutectic (α-Al+Al2Cu+Si) are observed. When the preheating temperature of the mold is changed to 500℃, 300℃, and 150℃, the greatest change is in the Si phase, and upon reaching the critical cooling rate, the ternary eutectic of (α-Al+Al2Cu+Si) forms. If the growth of the Si phase is suppressed upon the formation of (α-Al+Al2Cu+Si), the growth of both Al and Cu is also suppressed by a cooperative growth mechanism. As a result of analyzing the Al-27wt%Cu-5wt%Si ternary eutectic alloy with a different alloy design simulation programs, it was confirmed that different results arose depending on the program. A computer simulation of the alloy design is a useful tool to reduce the trial and error process in alloy design, but this effort must be accompanied by a task that increases reliability and allows a comparison to microstructural results derived through actual casting.

Interfacial Reaction between Ultra-Small 58Bi-42Sn Solder Bump and Au/Ni/Ti UBM for Ultra-Fine Flip Chip Application (고집적 플립 칩용 극미세 58Bi-42Sn 솔더 범프와 Au/Ni/Ti UBM의 계면 반응)

  • Kang, Woon-Byung;Jung, Yoon;Kim, Young-Ho
    • Journal of the Microelectronics and Packaging Society
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    • v.10 no.2
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    • pp.61-67
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    • 2003
  • The interfacial reaction between ultra-small 58Bi-42Sn solder and Au/Ni/Ti under bump metallurgy (UBM) for ultra-fine flip chip application was investigated. The ultra-small 58Bi-42Sn solder bump, about $46{\mu}m$ in diameter, was fabricated by using the lift-off method and reflowed using the rapid thermal annealing (RTA) system. The intermetallic compounds were characterized using a secondary electron microscopy (SEM), an energy dispersive spectroscopy (EDS), and an x-ray diffractometer (XRD). The faceted and polygonal intermetallic compounds were found in the Bi-Sn solder bumps on $Au(0.1{\mu}m)/Ni/Ti$ UBM and they were indentified as $(Au_xBi_yNi_{1-x-y})Sn_2$ Phase. The intermetallic compounds grown from the $Au(0.1{\mu}m)/Ni/Ti$ UBMinterface were dispersed in the solder bump.

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Study on Characteristic of CO2 Hydrate Formation Using Micro-sized Ice (미세직경 얼음을 이용한 CO2 하이드레이트 제조특성 연구)

  • Lee, Jong-Hyub;Kang, Seong-Pil
    • Korean Chemical Engineering Research
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    • v.50 no.4
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    • pp.690-695
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    • 2012
  • Gas hydrate is an inclusion compound consisting of water and low molecular weight gases, which are incorporated into the lattice structure of water. Owing to its promising aspect to application technologies, gas hydrate has been widely studied recently, especially $CO_2$ hydrate for the CCS (Carbon Capture and Storage) issue. The key point of $CO_2$ hydrate technology for the CCS is how to produce gas hydrate in an efficient and economic way. In this study, we have tried to study the characteristic of gas hydrate formation using micro-sized ice through an ultrasonic nozzle which generate 2.4 MHz frequency wave. $CO_2$ as a carrier gas brings micro-sized mist into low-temperature reactor, where the mist and carrier gas forms $CO_2$ hydrate under $-55^{\circ}C$ and atmospheric pressure condition and some part of the mist also remains unreacted micro-sized ice. Formed gas hydrate was average 10.7 of diameter at average. The starting ice particle was set to constant pressure to form $CO_2$ hydrate and the consumed amount of $CO_2$ gas was simultaneously measured to calculate the conversion of ice into gas hydrate. Results showed that the gas hydrate formation was highly suitable because of its extremely high gas-solid contact area, and the formation rate was also very high. Self-preservation effect of $CO_2$ hydrate was confirmed by the measurement of $CO_2$ hydrate powder at normal and at pressed state, which resulted that this kind of gas storage and transport could be feasible using $CO_2$ hydrate formation.

A Study on ASET Elongation & Notification Time to Fire Stations for the Escape Safety of Aged Bedridden Patients in Elderly Long-term Medical Care (노인의료복지시설 화재 시 와상노인의 피난안전성 제고를 위한 피난허용시간 연장과 소방기관으로의 통보시간 연구)

  • Park, Hyung-Joo;Lee, Young-Jae
    • Fire Science and Engineering
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    • v.32 no.4
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    • pp.50-59
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    • 2018
  • Recently, huge life losses occurred in the elderly long-term medical care fires due to lack of escape safety. As part of the measures to enhance the effectiveness of fire escape safety, while they prolong the available safe egress time (ASET) of non fire compartments, a measure to shorten fire-fighter's arrival time by fire alarm notifying device should be implemented in these facilities. The four categories from the aspects of fire prevention/protection engineering were provided with the necessary component technologies for carrying out these helper-guided evacuations. Fire prevention engineered technology was presented by two provisions; one for ensuring small compartment sections by installing the fire rated wall between bed rooms and another for ensuring the fire retardant or/and non-flammable performance of finishing materials. Also fire protection engineered technology was presented by two items; one for imposing cooling effects by sprinklers and another for providing automatic fire alarm notifying functions to fire stations. In order to improve the escape safety of these facilities in Korea, alternative revisions may presented by considering insufficient provisions in the architectural/fire law provisions by analyzing the provisions of Japanese and domestic laws in detail.

Magnetic Properties of Nylon 6 based Nd-Fe-Co-Zr-B Pellets for Injection Molding (사출성형용 Nylon 6계 Nd-Fe-Co-Zr-B 펠렛의 자기특성)

  • 최승덕;이우영;양충진
    • Journal of the Korean Magnetics Society
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    • v.3 no.1
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    • pp.34-40
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    • 1993
  • Nylon 6 based magnetic pellets for injection molding were produced using plasma arc melt-spun $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ powders. Two sorts of bonded magnets made of two different sizes of particles ($38~75\;\mu\textrm{m}$ and $75~150\;\mu\textrm{m}$) were prepared to determine critical volume fraction of magnet powders, and the magnetic prop erties of the magnets were discussed as a function of density. For the nylon fi based Nd-Fe-Co-Zr-B pellets made of $38~75\;\mu\textrm{m}$ particles, the critical volume fraction of powders 0.7 was obtained with the pellet density which is 90% of theoretical density while the magnets of $75~150\;\mu\textrm{m}$ showed the density of 87% of the theoretical value with the same volume fraction. The nylon (i magnets with the addition of 0.5 wt. % silicon oil only exhibited the best magnetic properties to have $_{i}H_{c}=8.8\;kOe,\;B_{r}=5.1\;kG$ and $(BH)_{max}=5.2\;MGOe$ which are of world class. An empirical relationship in predicting the magnet density with a known fraction ($V_s$) of loading powders was obtained such as ${\rho}(g/cm^{3})=1.1+K.V_{s}$ where the K ranges over 5.3~5.6 be ing dependent upon the particle size loaded.

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Changes of Indicator Microorganisms and Pathogenic Bacteria in Spinach during Cook-Chill Process (시금치의 cook-chill 가공 중 오염지표균 및 병원성세균의 변화)

  • Kim, Hye-Jung;Park, Jae-Kap;Lee, Dong-Sun;Paik, Hyun-Dong
    • Korean Journal of Food Science and Technology
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    • v.34 no.5
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    • pp.927-930
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    • 2002
  • Spinach minimally processed using cook-chill and sous vide techniques was vacuum-packed in low gas permeable plastic film, pasteurized at $70^{\circ}C$ for 2 min, cooled rapidly at $3^{\circ}C$, and stored at 3 and $10^{\circ}C$. Contents of mesophilic bacteria, psychrophilic bacteria, anaerobic bacteria, spore-forming bacteria, total coliforms, yeast and molds, fecal Streptococcus, and Enterobacteriacea were measared to identify the degree of food contamination. Number of mesophilic bacteria, detected at $2.2{\times}10^8\;cfu/g$ in raw spinish, decreased to about $6.0{\times}10^3\;cfu/g$ after cook-chill process. During the storage at 3 or $10^{\circ}C$, levels of mesophilic, psychrophilic and anaerobic bacteria increased, whereas total coliforms, yeast and molds, fecal Streptococcus, and Enterobacteriacea were not detected. Twelve strains of Aeromonas hydphila, Escherichia coli O157:H7, Plesiomonas shigelloides, Pseudomonas aeruginosa, Salmonella spp., Shigella spp., Yersinia enterocolitica, Bacillus cereus, Campylococcus spp., Clostridium perfringens, Listeria monocytogenes, and Staphylococcus aureus were examined for detecting the presence of pathogenic bacteria in spinach. B. cereus and C. perfringens were isolated from raw, washed, and cook-chilled spinach, whereas A. hydrophila was isolated only from washed spinach. S. aureus was isolated from raw and washed spinach, but not from cook-chilled spinach. Other pathogenic organisms were not detected in raw, washed, and cook-chilled spinach.

Properties of Quercus variabilis bio-oil prepared by sample preparation (시료 조건에 따른 굴참나무 바이오오일의 특성)

  • Chea, Kwang-Seok;Jo, Tae-Su;Choi, Seok-Hwan;Lee, Soo-Min;Hwang, Hye-Won;Choi, Joon-Weon
    • Journal of the Korean Applied Science and Technology
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    • v.32 no.1
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    • pp.148-156
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    • 2015
  • In this study the differences in the sample size and sample input changes as characteristics of bio-oil oak(Quercus variabilis), the oak 0.5~2.0 mm of the oak weighing 300~900g was processed into bio-oil via fast pyrolysis for 1.64 seconds. In this study, the physico-chemical properties of biooil using oak were investigated. Fast pyrolysis was adopted to increase the bio-oil yield from raw material. Although the differences in sample size and sample input changes in the yield of pyrolysis products were not significantly noticeable, increases in the yield of bio-oil accounted for approximately 60.3 to 62.1%, in the order of non-condensed gas, and biochar. When the primary bio-oil obtained by the condensation of the cooling tube and the seconary bio-oil obtained from the electric dust collector were measured separately, the yield of primary bio-oil was twice as higher than that of the secondary bio-oil. However, HHV (Higher Heating Value) of the secondary bio-oil was approximately twice as higher than that of the primary bio-oil by up to 5,602 kcal/kg. The water content of the primary bio-oil was more than 20% of the moisture content of the secondary bio-oil, which was 10% or less. In addition, the result of the elemental analysis regarding the secondary bio-oil, its primary carbon content was higher than that of the primary bio-oil, and since the oxygen content is low, the water content as well as elemental composition are believed to have an effect on the calorific value. The higher the storage temperature or the longer the storage period, the degree of the viscosity of the secondary bio-oil was higher than that of the primary bio-oil. This can be the attributed to the chemical bond between the polymeric bio-oil that forms during the storage period.

Developed an output device for high-frequency cosmetic medical equipment using micro multi-needle (마이크로 멀티니들을 이용한 고주파 피부미용 의료기기를 위한 출력 장치 개발)

  • Kim, Jun-tae;Joo, Kyu-tai;Cha, Eun Jong;Kim, Myung-mi;Jeong, Jin-hyoung
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.14 no.5
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    • pp.394-402
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    • 2021
  • The entry of an aging society and the extension of human life expectancy, the increasing interest in women's social advancement and men's appearance, and the natural interest in K-culture through media media, while receiving worldwide attention, Focus on K-Bueaty. Recently, looking at the occupation of the medical tourism field, in the case of aesthetic medicine tourism such as molding and dermatology, it has gained popularity not only in Asia such as China and Japan, but also in North America and Europe. The first external confirmation of human aging is the wrinkles on the skin of the face. Clean, wrinkle-free, elastic and healthy skin is a desire of most people. Skin condition and condition such as focused ultrasonic stimulation (HIFU: High Intensity Focused Utrasound) and low frequency, high frequency (RF: Radio Frequency), galvanic therapy using microcurrent, cryotherapy using rapid cooling, etc. Depending on the method of management, the effect of the treatment differs depending on the output and the stimulation site, etc., even in the treatment of medical equipment and beauty equipment using the same mechanism. In this research, in order to develop invasive high-frequency dermatological devices using a large number of beauty medical devices and microneedles of beauty devices, the international standards IEC 60601-2 (standards for individual medical devices) and MFDS (Ministry of) We designed and developed a high-frequency output device in compliance with the high-frequency stimulation standard announced in the Food and Drug Safety (Ministry of Food and Drug Safety). The circuit design consists of an amplifier (AMP: Amplifier) using Class-A Topology and a power supply device using Half-Bridge Topology. As a result of measuring the developed high-frequency output device, an average efficiency of 63.86% was obtained, and the maximum output was measured at 116.7W and 50.67dBm.