Formation of silicon nanoparticles by a pressure induced nucleation mechanism.

Kang, Myung-Koo,Kim, Si Joon,Kim, Hyun Jae RSC Pub 2013 Nanoscale Vol.5 No.8

<P>Formation of silicon nanoparticles (SiNPs) was achieved using excimer laser crystallization of an amorphous Si (a-Si) thin film using a SiO2 capping layer (C/L) with improved thin-film transistor (TFT) performance due to the enlarged grain size of polycrystalline Si (poly-Si). After laser irradiation of an a-Si thin film covered with C/L, fluctuation in the surface morphology of the C/L was observed above the critical laser energy density (Ecr) with the formation of SiNPs. The grain size of the poly-Si layer after crystallization increased abruptly at the same time. A non-uniform pressure distribution beneath the SiO2 C/L was proposed for the initiation of nucleation, which is named pressure induced nucleation (PIN) mechanism. Following nucleation, the release of latent heat made it difficult for the remnant liquid Si to solidify and the volume increased due to the density difference between the liquid and solid Si. Consequently, the pressure on the liquid Si caused SiNPs to sprout through the SiO2 C/L as grains grew from the low temperature to high temperature point. This study offers not only a simple method to fabricate SiNPs with controllable size/density but also larger grain size with lower laser energy density, which leads to higher TFT performance.</P>

적외선 분광법에 의한 양이온 교환된 Faujasite 의 T - O 결합특성

김명철,이시훈,김종택 한국화학공학회 1989 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.27 No.5

양이온 교환된 faujasite에 대하여 적외선 분광법, X선 회절분석 및 X선 형광분석법을 이용하여 연구하였다. 적외선 흡수띠의 이동이나 Si/Al비 및 결정성의 정도를 고찰하였다. 양이온 교환된 faujasite에 대한 적외선 흡수띠를 분해하먼 T-O(T : Al 또는 Si)의 진동파수가 940-1051㎝^(-1)(띠 A), 1000-1100㎝^(-1)(띠 B), 1097-1190㎝^(-1)(띠 C), 680-730㎝^(-1)(띠 D), 748-780㎝^(-1)(띠 E) 영역에서 나타났다. 띠 A와 E는 각각 Al-O의 비대칭 신축진동(υ_1) 및 대칭 신축진동(υ_2)에 의한 것으로 볼 수 있다. 띠 C와 D는 Si-O의 비대칭 신측진동(υ_3)과 대칭 신축진동(υ_2)에 의한 것으로 각각 보여진다. 띠 B는 Si-O의 비대칭 신축진동(υ_1)과 Al-O의 비대칭 신축진동(υ_3)의 띠가 겹쳐져서 나타난 것으로 볼 수 있다. The cation-exchanged faujasite were characterized and studied by infrared spectrometer, X-ray fluorescence spectrometer and X-ray diffractometer. The shift of i.r. absorption band, Si/Al ratio and degree of crystallinity were studied respectively. The deconvoluted bands of spectra for the cation-exchanged faujasite corresponding T-O vibration frequency appeared at 940-1050 ㎝^(-1) (band A), 1000-1100 ㎝^-1 (band B), 1097-1190 ㎝^-1 (band C), 680-730 ㎝^-1 (band D), and 748-780 ㎝^-1 (band E). The bands A and E were assigned to the asymmetric stretching(υ_1) and symmetric stretching (υ_2) of Al-O respectively. The bands C and D were assigned to the asymmetric stretching (υ_3) and symmetric stretching (υ_2) of Si-O respectively. The band B was assigned to the overlapping of asymmetric stretching (υ_1) of Si-O and asymmetric stretching (υ_3) of Al-O.

Controlled infiltration profile of SiC coating layer on graphite by Si vapor deposition reaction

Kuk-Jin Hwang,Si-Young Bae,Kyoung-Ho Kim,Yoon-Cheol Lee,Jung-Tae Hwang,Heesoo Lee,Seong Min Jeong,Myung-Hyun Lee 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.2

SiC-coated graphite was successfully fabricated at different temperatures (1300-1600 oC) through a silicon vapor depositionreaction (Si-VDR) process. Si powder was used for the Si source of the SiC coating layers. When Si powder was evaporatedat high temperature near the melting point of bulk Si, Si gases are moved and changed into Si liquid at the surface of thegraphite. The high-temperature process facilitated the formation of SiC coating layers on the graphite. The microstructural,mechanical, and thermal oxidation properties of the coated graphite were investigated.

개에 있어서 유선 종양의 1례

이시예,정성목,박창식,김명철 충남대학교 수의과대학 동물의과학연구소 2004 動物醫科學硏究誌 Vol.12 No.-

A 6-years-old 2.5kg female maltese dog with history of multiple mass around mammary gland was referred to Veterinary Medical Teaching Hospital, Chungnam National University. There was no evidence of metastasis in survey radiograph. Cytological finding revealed cell crumps of linear structures of epithelial cell origins. Histopathological finding revealed fibrous stroma, myxomatous lesion, catilagenous metaplasia, hyperplasia of lobular alveoli and ductules. Mass was removed by total mastectomy. After surgery, CBC values showed mild anemia, neutropenia and lymphocytosis. General condition was good. For the appropriate evaluation, more periodical and continuous monitoring is needed.

수평 구조의 냉전자 방출형 자기센서

남명우,김시헌,남태철 경북대학교 센서기술연구소 1995 센서技術學術大會論文集 Vol.6 No.1

We have fabricated the vacuum magnetic device with a lateral field emitter arrays constructed on n-Si wafer, and investigated its magnetic chracteristics. The devics is consisted of tip-arrayed emitter, gate, and split-anodes. The characteristics of the fabricated samples have been measured in the vacuum of 6.2X10^(-7) torr. A turn-on-voltage was approximately 84 V and anode current of 0.62 μA/tip was observed at the gate and the anode bias of 100 V and 200 V, respectively. Fowler-Nordheim plot could be obtained from the measurement, and field emitting area and field conversion factor calculated from the plot were 6.3X10^(-)16~1.2x10^(-15)cm^(2) and 8.9x10^(5)cm^(-1), respectively. The fabricated vacuum magnetic device has showed a good linearity to the magnetic field and a high sensitivity compared with the conventional semiconductor magnetic devices.

까치에 의하여 發生하는 配電線路의 故障豫防에 관한 硏究

전시식,장석구,심재명 한밭대학교 2004 한밭대학교 논문집 Vol.21 No.-

In modern times, electricity is an essential energy and its dependence to people is more increased. The distribution line system in Korea consists of 22.9kV multi-ground connection. The 15.2% of distribution line troubles is being produced by birds' contact with distribution line. The cause of the interruption of electric power is mostly a magpie. To prevent the troubles by magpie, various kinds of prevention measures have been tried for 20 years. But the trouble continues to be happened by magpie's outstanding ability of learning. In this paper, the effectiveness of prevention equipments using a sense of touch, sight and hearing which have been used at Korean Electric Power Corporation is analyzed and more effective prevention measures is considered. As a results, to prevent the troubles, it is difficult to get good effectiveness when only one prevention measure is applied. However, when several measures are applied at the same time, the troubles can be reduced. Also, even though magpies build their nests, for not to make the troubles, a electric pole equipment should be corrected and its form should be improved. In addition, we have found the facts that the activity periods for moderating the number of magpie and for removing the nests, weather, and DB system are simultaneously considered as the effective prevention measures.

색소혈관 모반증 2예

이명기,김시용,김영조 조선대학교 부설 의학연구소 1998 The Medical Journal of Chosun University Vol.23 No.2

Phacomatosis pigmentovascularis was recognized first as a syndrome that associated with cutaneous hemangioma and pigmentary nevus by Ota in 1947. Four type of the disorder are recognized, and they are subgrouped further by the presence(type b) or absence(type a) of systemic manifestations. We report here in two cases of phacomatosis pigmentovascularis. The first case was 19 year-old male who. since birth, has had three nevoid skin disorders: nevus flammeus, nevus anemicus, and aberrant mongolian spots. The second case was 16 year-old male who had nevus flammeus and pigmentary abnormality with deep vascular malformation. Our patients were diagnosed as having phacomatosis pigmentovascularis Ⅱ a because no visceral lesions were detected.

GIS를 이용한 산불발생위험지역 구분

이시영,안상현,원명수,이명보,임태규,신영철 한국지리정보학회 2004 한국지리정보학회지 Vol.7 No.2

산불로 인한 재해를 미연에 방지하고 피해를 저감하기 위해서는 산불발생위험지역을 사전에 파악하여 예방대책을 세울 필요가 있다. 따라서 본 연구에서는 산불발생인자에 따른 산불발생위험지역을 구분하고자 겸상북도 의성군에서 발생한 산불피해지역에 대하여 임상, 지형 등에 대하여 조사하였다. 조사된 요인들 간 독립성 유무를 상관분석을 이용하여 산불발생과 관련 있는 7개의 주제도를 선정하였으며, 선정된 주제도를 조건부확률과 지리정보시스템을 이용하여 산불발생확률을 계산하였다. 계산된 산불발생확률을 20개 등급으로 지수화하여 산불발생위험지역을 구분하였다. In order to decrease the area damaged by forest fires and to prevent the occurrence of forest fires, we are making an effort to improve prevention measures for forest fires. The objective of this study is to classify hazard regions where forest fires occur based on the factors that contribute to the occurrence of forest fires. Forest fire sites in the Uiseong-gun, Gyeongsangbuk-do were surveyed according to the factors of forest type and topographic characteristics where the forest fires occurred. We used a correlation analysis to determine the forest fire occurrence factors and a conditional probability analysis and GIS to determine a forest fire danger index. The resulting forest fire danger index was used in the classification of forest fire occurrence risk regions.

개에 있어서 유선 종양의 1례

이시예,정성목,박창식,김명철 충남대학교 형질전환복제돼지연구센터 2007 논문집 Vol. No.10

A 6-years-old 2.5kg female maltese dog with history of multiple mass around mammary gland was referred to Veterinary Medical Teaching Hospital. Chungnam National University. There was no evidence of metastasis in survey radiograph. Cytological finding revealed cell crumps of linear structures of epithelial cell origins. Histopathological finding revealed fibrous stroma. myxomatous lesion. catilagenous metaplasia. hyperplasia of lobular alveoli and ductules. Mass was removed by total mastectomy. After surgery, CBC values showed mild anemia. neutropenia and lymphocytosis. General condition was good. For the appropriate evaluation, more periodical and continuous monitoring is needed.

기능성 위장관 장애에서 혈청 IL-1β, IL-2,IL-6의 변화 : 우울증 및 스트레스와의 상관성

박시성,이상신,박무인,구자영,박제민,김명정 한국정신신체의학회 2002 정신신체의학 Vol.10 No.2