• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
• /
• pp.441-443
• /
• 2005

According as CCFL(Cold Cathode Fluorescent lamp) of light source in Backlight unit for Note PC (Personal computer) is presently needed to low power consumption and long life time, the development focus of CCFL is going on the discharge gas, phosphor and electrode material. First of all, discharge voltage characteristic of CCFL is closely connected with electrode material For low discharge voltage, the characteristic of electrode material is needed to low work function, low sputtering ratio and superior manufacturing property. We developed new CCFL with Nb/Ni Clad electrode superior to conventional CCFL. Because Nb/Ni Clad electrode with Ni material and Nb material, the electrical characteristic is superior to other electrode materials. The electrode of Nb/Ni Clad is composed that Ni of outside material has superior manufacturing property and Nb of inside material has low work function. Nb/Ni Clad of new electrode material is made by process of Rolling mill at high pressure and heat treatment. We compared electrical characteristic of Nb/Ni clad electrode with conventional Mo electrode by measurement. Mo electrode and Nb/Ni Clad electrode of cup type with diameter 1.1 mm and length 3.0mm are used to this experiment. Material content of Mo electrode is Mo 100%. But, Nb/Ni Clad electrode is composed by content of Nb 40% and Ni 60%. The result of comparison measurement between new CCFL with Nb/Ni Clad electrode and conventional CCFL was appeared that CCFL with Nb/Ni Clad electrode had superior characteristic than conventional CCFL. As a result of experiment, we completed Note PC with low power consumption and long life time by application of new CCFL with Nb/Ni Clad electrode.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
• /
• pp.20-20
• /
• 2003

We developed 30 ㎽-AlInGaN based violet laser diodes. The fabrication procedures of the laser diodes are described as follows. Firstly, GaN layers having very low defect density were grown on sapphire substrates by lateral epitaxial overgrowth method. The typical dislocation density was about 1-3$\times$10$^{6}$ /$\textrm{cm}^2$ at the wing region. Secondly, AlInGaN laser structures were grown on LEO-GaN/sapphire substrates by MOCVD. UV activation method, instead of conventional annealing, was conducted to achieve good p-type conduction. Thirdly, ridge stripe laser structures were fabricated. The cavity mirrors were formed by cleaving method. Three pairs of SiO$_2$ and TiO$_2$ layers were deposited on the rear facet for mirror coating. Lastly, laser diode chips were mounted on AlN submount wafers by epi-down bonding method. The lifetime of the laser diodes was over 10,000 hrs at room temperature under automatic power controlled condition. We expect the performance of the LDs to be improved by the optimization of the growth and fabrication process. The detailed characteristics and important issues of the laser diodes will be discussed at the conference.

• Genomics & Informatics
• /
• 제21권4호
• /
• pp.44.1-44.10
• /
• 2023

Tumor hypoxia, oxygen deprivation state, occurs in most cancers and promotes angiogenesis, enhancing the potential for metastasis. The vascular endothelial growth factor (VEGF) family genes play crucial roles in tumorigenesis by promoting angiogenesis. To investigate the malignant processes triggered by hypoxia-induced angiogenesis across pan-cancers, we comprehensively analyzed the relationships between the expression of VEGF family genes and hypoxic microenvironment based on integrated bioinformatics methods. Our results suggest that the expression of VEGF family genes differs significantly among various cancers, highlighting their heterogeneity effect on human cancers. Across the 33 cancers, VEGFB and VEGFD showed the highest and lowest expression levels, respectively. The survival analysis showed that VEGFA and placental growth factor (PGF) were correlated with poor prognosis in many cancers, including kidney renal cell and liver hepatocellular carcinoma. VEGFC expression was positively correlated with glioma and stomach cancer. VEGFA and PGF showed distinct positive correlations with hypoxia scores in most cancers, indicating a potential correlation with tumor aggressiveness. The expression of miRNAs targeting VEGF family genes, including hsa-miR-130b-5p and hsa-miR-940, was positively correlated with hypoxia. In immune subtypes analysis, VEGFC was highly expressed in C3 (inflammatory) and C6 (transforming growth factor β dominant) across various cancers, indicating its potential role as a tumor promotor. VEGFC expression exhibited positive correlations with immune infiltration scores, suggesting low tumor purity. High expression of VEGFA and VEGFC showed favorable responses to various drugs, including BLU-667, which abrogates RET signaling, an oncogenic driver in liver and thyroid cancers. Our findings suggest potential roles of VEGF family genes in malignant processes related with hypoxia-induced angiogenesis.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
• /
• pp.115-116
• /
• 2012

The demand for flexible electronic systems such as wearable computers, E-paper, and flexible displays has increased due to their advantages of excellent portability, conformal contact with curved surfaces, light weight, and human friendly interfaces over present rigid electronic systems. This seminar introduces three recent progresses that can extend the application of high performance flexible inorganic electronics. The first part of this seminar will introduce a RRAM with a one transistor-one memristor (1T-1M) arrays on flexible substrates. Flexible memory is an essential part of electronics for data processing, storage, and radio frequency (RF) communication and thus a key element to realize such flexible electronic systems. Although several emerging memory technologies, including resistive switching memory, have been proposed, the cell-to-cell interference issue has to be overcome for flexible and high performance nonvolatile memory applications. The cell-to-cell interference between neighbouring memory cells occurs due to leakage current paths through adjacent low resistance state cells and induces not only unnecessary power consumption but also a misreading problem, a fatal obstacle in memory operation. To fabricate a fully functional flexible memory and prevent these unwanted effects, we integrated high performance flexible single crystal silicon transistors with an amorphous titanium oxide (a-TiO2) based memristor to control the logic state of memory. The $8{\times}8$ NOR type 1T-1M RRAM demonstrated the first random access memory operation on flexible substrates by controlling each memory unit cell independently. The second part of the seminar will discuss the flexible GaN LED on LCP substrates for implantable biosensor. Inorganic III-V light emitting diodes (LEDs) have superior characteristics, such as long-term stability, high efficiency, and strong brightness compared to conventional incandescent lamps and OLED. However, due to the brittle property of bulk inorganic semiconductor materials, III-V LED limits its applications in the field of high performance flexible electronics. This seminar introduces the first flexible and implantable GaN LED on plastic substrates that is transferred from bulk GaN on Si substrates. The superb properties of the flexible GaN thin film in terms of its wide band gap and high efficiency enable the dramatic extension of not only consumer electronic applications but also the biosensing scale. The flexible white LEDs are demonstrated for the feasibility of using a white light source for future flexible BLU devices. Finally a water-resist and a biocompatible PTFE-coated flexible LED biosensor can detect PSA at a detection limit of 1 ng/mL. These results show that the nitride-based flexible LED can be used as the future flexible display technology and a type of implantable LED biosensor for a therapy tool. The final part of this seminar will introduce a highly efficient and printable BaTiO3 thin film nanogenerator on plastic substrates. Energy harvesting technologies converting external biomechanical energy sources (such as heart beat, blood flow, muscle stretching and animal movements) into electrical energy is recently a highly demanding issue in the materials science community. Herein, we describe procedure suitable for generating and printing a lead-free microstructured BaTiO3 thin film nanogenerator on plastic substrates to overcome limitations appeared in conventional flexible ferroelectric devices. Flexible BaTiO3 thin film nanogenerator was fabricated and the piezoelectric properties and mechanically stability of ferroelectric devices were characterized. From the results, we demonstrate the highly efficient and stable performance of BaTiO3 thin film nanogenerator.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 하계학술대회 논문집
• /
• pp.311-311
• /
• 2009

Carbon nanotubes (CNTs) belong to an ideal material for field emitters because of their superior electrical, mechanical, and chemical properties together with unique geometric features. Several applications of CNTs to field emitters have been demonstrated in electron emission devices such as field emission display (FED), backlight unit (BLU), X-ray source, etc. In this study, we fabricated a CNT cathode by using filtration processes. First, an aqueous CNT solution was prepared by ultrasonically dispersing purified single-walled CNTs (SWCNTs) in deionized water with sodium dodecyl sulfate (SDS). The aqueous CNT solution in a milliliter or even several tens of micro-litters was filtered by an alumina membrane through the vacuum filtration, and an ultra-thin CNT film was formed onto the alumina membrane. Thereafter, the alumina membrane was solvated by acetone, and the floating CNT film was easily transferred to indium-tin-oxide (ITO) glass substrate in an area defined as 1 cm with a film mask. The CNT film was subjected to an activation process with an adhesive roller, erecting the CNTs up to serve as electron emitters. In order to measure their luminance characteristics, an ITO-coated glass substrate having phosphor was employed as an anode plate. Our field emitter array (FEA) was fairly transparent unlike conventional FEAs, which enabled light to emit not only through the anode frontside but also through the cathode backside, where luminace on the cathode backside was higher than that on the anode frontside. Futhermore, we added a reflecting metal layer to cathode or anode side to enhance the luminance of light passing through the other side. In one case, the metal layer was formed onto the bottom face of the cathode substrate and reflected the light back so that light passed only through the anode substrate. In the other case, the reflecting layer coated on the anode substrate made all light go only through the cathode substrate. Among the two cases, the latter showed higher luminance than the former. This study will discuss the morphologies and field emission characteristics of CNT emitters according to the experimental parameters in fabricating the lamps emitting light on the both sides or only on the either side.

• 대한치과보철학회지
• /
• 제38권2호
• /
• pp.242-254
• /
• 2000

Accurate impression is very important to achieve desirable prosthesis and there are many factors in taking a good impression. For example, types of impression material, types of impression tray, impression taking methods and so on. Recently individual tooth tray technique is accepted as obtaining good impression that can be applied to multiple abutment impression, heavy salivated patient, to minimize the effect of natural teeth s undercuts and to reduce pain during cord packing procedures. The purpose of this study was to compare the accuracy according to materials and forms of the individual tooth tray which is clinically applied nowadays. Used materials in experiment were divided into 3 types (acrylic resin. $Futar^{(R)}$ occlusion. $Blu-mousse^{(R)}$) and forms were divided into 2 types (forming occlusal vent hole or not and forming marginal vent space or not). Stone master model from impression body and metal master model were measured by $X-PLAN360d^{(R)}$ to compare occlusal surface discrepancy and marginal discrepancy. The results were as follows: 1. In comparison of occlusal surface discrepancy and marginal discrepancy according to materials, groups with three materials showed no statistical difference 2. In comparison of occlusal surface discrepancy and marginal discrepancy according to occlusal vent hole, groups with occlusal vent hole showed significantly less marginal discrepancy than groups with no occlusal vent hole(p<0.05). 3. In comparison of occlusal surface discrepancy and marginal discrepancy according to 0.5mm-marginal-vent-space, groups with no 0.5mm-marginal-vent-space showed significantly less marginal discrepancy than groups with 0.5mm-marginal-vent-space (p<0.05). In summary these results suggest that individual tooth tray made of 3 types of materials with occlusal vent hole and individual tooth tray made of acrylic resin with no marginal vent space showed good accuracy of impression. In addition, individual tooth tray which is made of bite registration materials may be more useful because of advantage in facility and timesaving aspect of fabrication.

• 한국치위생학회지
• /
• 제12권3호
• /
• pp.513-520
• /
• 2012

Objectives : In this study, contact angle and shore D hardness were measured, and a shark fin test was conducted after selecting five addition silicon(Blu-Mousse, BM; EXABITE II, EX; PERFECT, PF; Regisil$^{(R)}$ Rigid, RE; Silagum$^{(R)}$, SI) in order to figure out the properties of elastomeric interocclusal recording materials and reduce errors at interocclusal recording. 8) Methods : A contact angle was measured using a contact angle analyzer. After placing a drop of liquid on the surface of the specimens of interocclusal recording materials, a contact angle was photographed with a CCD camera on the equipment. In terms of a shark fin test, interocclusal recording materials were mixed for the time proposed by the manufacturer and inserted into the split ring of the Shark fin device. Twenty (20) seconds exactly, a metal rod was removed to make the materials slowly absorbed. Once they hardened, fin height was measured with a caliper after separating molds and trimming the specimens. The shore D hardness was measured with a shore D hardness tester(Model HPDSD, Hans Schmidt & Co. Gmbh, Germany) in sixty (60) minutes after fabricating specimens. In each experiment, five specimens, mean and standard deviation were calculated. A one-way ANOVA test was performed at the p>0.05 level of significance. In terms of correlation among the tests, Pearson correlation coefficient was estimated. For multiple comparison, Scheffe's test was carried out. Results : A contact angle was the highest in EX with $99.23^{\circ}$ (p<0.05) while the result of the shark fin test was the longest in RE with 5.45mm. SI was the lowest (0.27mm) with statistical significance. Among the interocclusal recording materials, significant difference was observed in terms of means (p<0.05). The shore D hardness was the highest in SI with 31.0 while RE was significantly low with 16.4 (p<0.05). Among the materials, statistically significant difference was observed in terms of means when compared to the rest materials (RE), BM, RE and SI (PF and EX) and the remaining materials (BM and SI) (p<0.05). In terms of correlations among the tests, a negative correlation occurred between shore D hardness and shark fin test(r=-0.823, p=0.000). Conclusions : According to the study above, it is necessary to understand the properties of interocclusal recording materials and consider contact angle, shark fin test and properties of shore D hardness to select appropriate materials.

• 융합신호처리학회논문지
• /
• 제11권1호
• /
• pp.32-40
• /
• 2010

확장된 네이보어-제르니케 방법을 이용하여 광학계의 동공함수(pupil function)를 추산하는 알고리즘을 제안한다. 동공함수로부터 광학계가 가진 파면수차를 복원하고 아울러 동공에 비추어지는 빛의 밝기분포를 분석할 수 있다. 이 방법은 브루-레이 광픽업의 생산현장에 적용하여 실시간으로 광학계의 수차를 복원할 수 있다. 아울러 이 방법이 여러 다른 광학계에 널리 이용될 수 있음을 다양하게 수차를 부여해서 생성한 데이터를 분석하여 검증하였다. 초점영역의 빔 데이터로부터 동공함수를 얻는 역변환의 여러 방법 중에서 수차이론에 근거한 기존의 네이보어-제르니케 방법을 최근에 네덜란드 연구진이 개량한 확장된 네이보어-제르니케(extended Nijboer-Zernike: ENZ) 방법을 제안하였다. ENZ 방법은 초점영역의 3차원 빔 데이터로부터 해석적인 접근을 통하여 동공의 제르니케 계수를 효율적으로 계산해 낸다. 그러나 이 방법에서는 개구수(NA)가 큰 경우에는 근사적인 접근을 하도록 되어 있다. 본 연구에서는 보다 일반적인 상황에서 적용할 수 있는 수치해석 알고리즘을 개발하고, 이를 GUI 환경에서 운용할 수 있는 윈도 기반의 프로그램을 작성하여 생성한 빔 데이터에 적용하여 이 알고리즘의 유효성을 검증하여 13개의 복소 수차인자 $\beta_n^m$이 모든 요소가 0.7까지 분석을 하였고, 아울러 광픽업의 3D 빔 데이터를 실측해서 간섭계로 측정한 데이터와 R=0.98 정도의 상관관계를 가지는 것을 확인하였다.

• 한국안광학회지
• /
• 제18권3호
• /
• pp.297-304
• /
• 2013

목적: 광원에 따른 청광차단렌즈의 청광차단율과 청광비율을 조사하고, 이를 활용한 청광차단렌즈의 처방에 대하여 고찰하였다. 방법: 광원에 따른 청광차단렌즈의 청광차단율과 청광비율의 조사를 위해 UV-VIS 분광광도계를, 청광차단렌즈와 관련된 처방을 평가하는 기준으로 태양광에 대한 청광비율을 이용하였다. 결과: 렌즈의 청광차단율과 청광비율은 광원에 따라 다르게 나타났다. 모든 BLU 광원의 청광비율은 태양광($D_{65}$ 광원)의 청광비율보다 큰 것으로 확인되었다. 태양광의 청광비율과 렌즈 투과광의 청광비율을 통해 각 광원에 적합한 청광차단렌즈들을 선별할 수 있었다. 결론: 청광차단렌즈 처방에 있어서 렌즈의 청광차단율과 청광비율이 광원에 의존하므로 사용자의 광원에 대한 문진이 선행되어야 한다. 태양광의 청광비율에 기준한 렌즈 투과광의 청광비율은 청광차단렌즈의 처방과 관련된 하나의 평가 방법으로 유용하게 활용될 수 있다.

• 한국식품위생안전성학회지
• /
• 제18권3호
• /
• pp.125-132
• /
• 2003

1999년 2월부터 2000년 11월까지 남해안의 패류양식장에서 채취한 굴(Crassostrea gigas), 진주담치(Mytilus edulis), 바지락(Ruditapes philippinarum) 및 피조개(Scapharca broughtonii)의 수은, 카드뮴, 납 및 크롬 등 중금속 함량을 정량하고 굴과 진주담치간의 중금속 함량을 비교하였다. 남해안 11개소의 패류 양식장에서 채취한 굴의 중금속 함량은 평균치로 수은이 0.008 ${\mu}g/g$, 카드뮴이 0.519 ${\mu}g/g$, 납이 0.220 ${\mu}g/g$ 그리고 크롬이 0.153 ${\mu}g/g$이었고, 12개소에서 채위한 진주담치의 함량은 각각 0.008, 0.257, 0.214 및 0.178 ${\mu}g/g$이었다. 전남 고흥군 나로도 연안에서 채취한 바지락의 중금속 함량은 평균치로 수은이 0.009 ${\mu}g/g$, 카드뮴이 0.232 ${\mu}g/g$, 납이 0.107 ${\mu}g/g$ 크롬이 0.364 ${\mu}g/g$이었고, 경남 남해 강진만에서 채취한 피고개의 함량은 각각 0.007, 0.559, 0.149 및 0.116 ${\mu}g/g$이었다. 굴, 진주담치, 바지락 및 피조개에서 검출된 중금속의 함량은 최고치인 경우에 있엇도 우리나라의 해산 패류 중 중금속 허용기준치 및 미국의 패류에서의 중금속 농도 권고치를 초과하지 않았다. 동일한 지역에서 같은 시기에 채취한 굴과 진주담치는 수은의 함량은 거의 차이가 없었으나 카드뮴은 굴이 진주담치보다 약 2배의 축적율을 나타내어 품종에 따른 차이가 뚜렷하였다.