• 자원리싸이클링
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• 제24권4호
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• pp.50-55
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• 2015

본 연구에서는 LED 칩 제조를 위해 이용되는 유기금속화학증착(MOCVD) 장비에서 발생하는 분진(dust)으로부터 용매추출을 통해 고순도 갈륨(Ga) 함유 수용액을 회수하는 연구를 수행하였다. 추출제 종류, 추출제의 농도 변화에 대한 연구를 통해 Ga 추출에 효과적인 추출제를 선정하고자 하였으며 다단계 추출/역추출 공정을 통해 추출 효율을 향상시켜 고순도 Ga 수용액을 제조하였다. 선행연구에서 원료에 대한 분석을 바탕으로 Ga의 추출 및 분리를 위해 PC88A, DP-8R, Cyanex 272 추출제 중 Cyanex 272를 선택하였으며 1.5M일 때 43.8%의 효율이 나타났다. 다단계 추출을 통해 Ga의 추출 효율은 83%까지 상승하였으며 0.1 M HCl을 이용한 역추출 공정으로 불순물이 없는 5N급 고순도 Ga 수용액을 제조할 수 있었다.

• 한국표면공학회지
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• 제48권5호
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• pp.211-217
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• 2015

To fabricate white LED having a high color rendering index value, red color phosphor mixed with the green color phosphor together in the blue chip, namely the blue chips with RG phosphors packaging is most favorable for high power white LEDs. In our previous papers, we reported on successful syntheses of $Sr_{2-}$ $Si_5N_8:Eu^{2+}$ and $CaAlSiN_3$ phosphors for red phosphor. In this work, for high power green phosphor, greenemitting ternary nitride $Ba_3Si_6O_{12}N_2:Eu^{2+}$ phosphor was synthesized in a high frequency induction furnace under $N_2$ gas atmosphere at temperatures up to $1400^{\circ}C$ using $EuF_3$ as a raw material for $Eu^{2+}$ dopant. The effects of molar ratio of component and experimental conditions on luminescence property of prepared phosphors have been investigated. The structure and luminescence properties of prepared $Ba_3Si_6O_{12}N_2:Eu^{2+}$ phosphors were investigated by XRD and photoluminescence spectroscopy. The excitation spectra of $Ba_3Si_6O_{12}N_2:Eu^{2+}$ phosphors indicated broad excitation wavelength range of 250 - 500 nm, namely from UV to blue region with distinct enhanced emission spectrum peaking at ${\approx}530nm$.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.967-970
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• 2008

우리나라 암 발생빈도 중 간암은 위암에 이어 두 번째로 흔한 암으로, 초기에는 특이 증상이나 증후 없이 서서히 진행되는 경우가 많아 증상이 생긴 후 간암으로 진단될 경우, 대부분 마땅한 치료방법이 별로 없어 어떠한 치료를 해도 환자의 예후는 불량하나, 조기에 발견될 경우는 치료성적이 우수하여 조기 발견이 대단히 중요시된다. 본 시스템은 간암의 조기발견을 위한 시스템으로, 간암으로 확진된 환자와 간암이외의 대조군의 혈액을 바이오침에 반응시켜 바이오칩 프로파일을 기계학습을 통해 분류하는 시스템이다. 본 논문에서는 총 50샘플로 구성된 간암환자 와 100샘플로 구성된 간암 이외의 대조군의 혈액시료를 1149의 서로 다른 올리고로 구성된 바이오칩에 반응시켜 획득한 데이터를 인공신경 망을 통해 분석한 결과 $92{\sim}96%$의 분류 성능을 보였다.

• 한국생물정보학회:학술대회논문집
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• 한국생물정보시스템생물학회 2001년도 제2회 생물정보 워크샵 (DNA Chip Bioinformatics)
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• pp.61-86
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• 2001

All cancers are caused by abnormalities in DNA sequence. Throughout life, the DNA in human cells is exposed to mutagens and suffers mistakes in replication, resulting in progressive, subtle changes in the DNA sequence in each cell. Since the development of conventional and molecular cytogenetic methods to the analysis of chromosomal aberrations in cancers, more than 1,800 recurring chromosomal breakpoints have been identified. These breakpoints and regions of nonrandom copy number changes typically point to the location of genes involved in cancer initiation and progression. With the introduction of molecular cytogenetic methodologies based on fluorescence in situ hybridization (FISH), namely, comparative genomic hybridization (CGH) and multicolor FISH (m-FISH) in carcinomas become susceptible to analysis. Conventional CGH has been widely applied for the detection of genomic imbalances in tumor cells, and used normal metaphase chromosomes as targets for the mapping of copy number changes. However, this limits the mapping of such imbalances to the resolution limit of metaphase chromosomes (usually 10 to 20 Mb). Efforts to increase this resolution have led to the "new"concept of genomic DNA chip (1 to 2 Mb), whereby the chromosomal target is replaced with cloned DNA immobilized on such as glass slides. The resulting resolution then depends on the size of the immobilized DNA fragments. We have completed the first draft of its Korean Genome Project. The project proceeded by end sequencing inserts from a library of 96,768 bacterial artificial chromosomes (BACs) containing genomic DNA fragments from Korean ethnicity. The sequenced BAC ends were then compared to the Human Genome Project′s publicly available sequence database and aligned according to known cancer gene sequences. These BAC clones were biotinylated by nick translation, hybridized to cytogenetic preparations of metaphase cells, and detected with fluorescein-conjugated avidin. Only locations of unique or low-copy Portions of the clone are identified, because high-copy interspersed repetitive sequences in the probe were suppressed by the addition of unlabelled Cotl DNA. Banding patterns were produced using DAPI. By this means, every BAC fragment has been matched to its appropriate chromosomal location. We have placed 86 (156 BAC clones) cytogenetically defined landmarks to help with the characterization of known cancer genes. Microarray techniques would be applied in CGH by replacement of metaphase chromosome to arrayed BAC confirming in oncogene and tumor suppressor gene: and an array BAC clones from the collection is used to perform a genome-wide scan for segmental aneuploidy by array-CGH. Therefore, the genomic DNA chip (arrayed BAC) will be undoubtedly provide accurate diagnosis of deletions, duplication, insertions and rearrangements of genomic material related to various human phenotypes, including neoplasias. And our tumor markers based on genetic abnormalities of cancer would be identified and contribute to the screening of the stage of cancers and/or hereditary diseases

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.102-102
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• 2018

Electronic industry had required the finer size and the higher performance of the device. Therefore, 3-D die stacking technology such as TSV (through silicon via) and micro-bump had been used. Moreover, by the development of the 3-D die stacking technology, 3-D structure such as chip to chip (c2c) and chip to wafer (c2w) had become practicable. These technologies led to the appearance of HBM (high bandwidth memory). HBM was type of the memory, which is composed of several stacked layers of the memory chips. Each memory chips were connected by TSV and micro-bump. Thus, HBM had lower RC delay and higher performance of data processing than the conventional memory. Moreover, due to the development of the IT industry such as, AI (artificial intelligence), IOT (internet of things), and VR (virtual reality), the lower pitch size and the higher density were required to micro-electronics. Particularly, to obtain the fine pitch, some of the method such as copper pillar, nickel diffusion barrier, and tin-silver or tin-silver-copper based bump had been utillized. TCB (thermal compression bonding) and reflow process (thermal aging) were conventional method to bond between tin-silver or tin-silver-copper caps in the temperature range of 200 to 300 degrees. However, because of tin overflow which caused by higher operating temperature than melting point of Tin ($232^{\circ}C$), there would be the danger of bump bridge failure in fine-pitch bonding. Furthermore, regulating the phase of IMC (intermetallic compound) which was located between nickel diffusion barrier and bump, had a lot of problems. For example, an excess of kirkendall void which provides site of brittle fracture occurs at IMC layer after reflow process. The essential solution to reduce the difficulty of bump bonding process is copper to copper direct bonding below $300^{\circ}C$. In this study, in order to improve the problem of bump bonding process, copper to copper direct bonding was performed below $300^{\circ}C$. The driving force of bonding was the self-annealing properties of electrodeposited Cu with high defect density. The self-annealing property originated in high defect density and non-equilibrium grain boundaries at the triple junction. The electrodeposited Cu at high current density and low bath temperature was fabricated by electroplating on copper deposited silicon wafer. The copper-copper bonding experiments was conducted using thermal pressing machine. The condition of investigation such as thermal parameter and pressure parameter were varied to acquire proper bonded specimens. The bonded interface was characterized by SEM (scanning electron microscope) and OM (optical microscope). The density of grain boundary and defects were examined by TEM (transmission electron microscopy).

• 생명과학회지
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• 제26권7호
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• pp.826-834
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• 2016

본 연구는 Hsp90 inhibitor 및 SIRT1 inhibitor의 병용처리가 항암제 다제내성(MDR) 인간 암세포의 증식 억제에 효과적임을 밝혔다. SIRT1 활성 억제가 Hsp90 inhibitor인 17-AAG의 세포 독성의 효과를 증강시켰으며, 이로 인해 Hsp90 inhibitors에 대한 내성을 극복시킬 수 있음을 인간 자궁암세포인 HeyA8의 MDR 변이주인 HeyA8- MDR 세포에서 확인하였다. SIRT1 inhibitor는 Hsp90 inhibitor에 의한 Hsp90 샤페론 기능 억제를 증강시키며, ubiquitin ligase CHIP의 발현 증강을 유발하여, Hsp90 client protein 인 mutant p53 (mut p53)의 분해를 촉진시킨다. Mut p53 의 발현 감소는 암세포의 Hsp90 inhibitor 내성 획득의 가장 중요한 원인으로 지적되는 heat shock factor 1 (HSF1)/heat shock proteins (Hsps)의 발현 억제와 관련됨을 알 수 있었으며, 이는 항암제 다제내성 세포에서 SIRT1 inhibitor에 의하여 Hsp90 inhibitor에 대한 감수성이 증강되는 분자적 기전임을 밝혔다. 그러므로, SIRT1 억제에 의한 mut p53/HSF1 발현 감소가 MDR 암세포의 Hsp90 inhibitors 내성 극복에 매우 유효함을 시사하는 결과를 얻었다.

• 전기전자학회논문지
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• 제22권1호
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• pp.189-192
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• 2018

본 연구에서는 LED칩 및 LCD 검사장비의 핵심부품인 광학 필름제조에 많이 사용되고 있는 DBR(Distributed Bragg Reflectors) 구조에 대한 시뮬레이션 방법을 개발하고 이러한 다층박막 특성 시뮬레이션을 통하여 최적의 DBR 구조를 제시하였다. 고굴절률 유전체인 $TiO_2$와 저굴절률 유전체인 $SiO_2$ 박막을 교대로 적층한 다층박막 구조에서 $TiO_2$와 $SiO_2$의 refractive index 값을 사용하여 박막의 배치 및 조합에 따른 wavelength(nm) vs. reflectance(%) 스펙트럼을 계산하였고 이 결과로 시뮬레이션을 통한 고효율 분산 브래그 반사경 최적화 설계 및 공정에 활용하여 DBR 구조 제작에 사용할 수 있었다.

• Food Science and Biotechnology
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• 제17권5호
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• pp.1038-1046
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• 2008

This study was carried out to develop a small-sized biosensor based on surface plasmon resonance (SPR) for the rapid identification of insecticide residues for food safety. The SPR biosensor module consists of a single 770 nm-light emitting diodes (LED) light source, several optical lenses for transferring light, a hemisphere sensor chip, photo detector, A/D converter, power source, and software for signal processing using a computer. Except for the computer, the size and weight of the sensor module are 150 (L)$\times$70 (W)$\times$120 (H) mm and 828 g, respectively. Validation and application procedures were designed to assess refractive index analysis, affinity properties, sensitivity, linearity, limits of detection, and robustness which includes an analysis of baseline stability and reproducibility of ligand immobilization using carbamate (carbofuran and carbaryl) and organophosphate (cadusafos, ethoprofos, and chlorpyrifos) insecticide residues. With direct binding analysis, insecticide residues were detected at less than the minimum 0.01 ppm and analyzed in less than 100 sec with a good linear relationship. Based on these results, we find that the binding interaction with active target groups in enzymes using the miniaturized SPR biosensor could detect low concentrations which satisfy the maximum residue limits for pesticide tolerance in Korea, Japan, and the USA.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.24-24
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• 2003

Research activity in the III-V nitrides materials system has increased markedly in the past several years ever since high-brightness blue light-emitting diodes (LEDs) became commercially available. Despite of excellent optical properties of the GaN, however, inherently poor thermal property of the sapphire used as a substrate material n these devices may lead to thermal degradation of devices, especially during their high power operation. Therefore, dependable thermal analysis and packaging schemes of GaN-based LEDs are necessary for solid lighting applications under high power operation. In this paper, emphasis will be placed upon thermal design of GaN-based LEDs. Thermal measurements of LEDs on chip and packaging scale were performed using the liquid crystal thermographic technology and micro thermocouples for different bias conditions. By a series of optical arrangement, hot spots with specific transition temperatures were obtained with increasing input power. Thermal design of LEDS was made using the finite element method and analytical unit temperature profile approach with optimal boundary conditions. The experimental results were compared to the simulated data and the results agree well enough for the establishment of dependable prediction of thermal behavior in these devices. The paper will present a more detailed understanding of the thermal analysis of the GaN-based blue and white LEDs for high power applications.

• 한국전기전자재료학회논문지
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• 제23권9호
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• pp.667-670
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• 2010

In this paper, a high voltage current sensing circuit for boost converter is designed and verified by Cadence SPECTRE simulations. The current mirror pair, power and sensing metal-oxide semiconductor field effect transistors (MOSFETs) with size ratio of K, is used in our on-chip current sensing circuit. Very low drain voltages of the current mirror pair should be matched to give accurate current sensing, so a folded-cascode opamp with a PMOS input pair is used in our design. A high voltage high side lateral-diffused MOS transistor (LDMOST) switch is used between the current sensing circuit and power MOSFET to protect the current sensing circuit from the high output voltage. Simulation results using 0.35 ${\mu}m$ BCD process show that current sensing is accurate and the pulse frequency modulation (PFM) boost converter using the proposed current sensing circuit satisfies with the specifications.