• Journal of the Microelectronics and Packaging Society
• /
• v.31 no.1
• /
• pp.35-42
• /
• 2024

Recently, with the miniaturization and high integration of semiconductor chips, the bump bridge phenomenon caused by fine pitches is drawing attention as a problem. Accordingly, Cu pillar bump, which can minimize the bump bridge phenomenon, is widely applied in the semiconductor package industry for fine pitch applications. When exposed to a high-temperature environment, the thickness of the intermetallic compound (IMC) formed at the joint interface increases, and at the same time, Kirkendall void is formed and grown inside some IMC/Cu and IMC interfaces. Therefore, it is important to control the excessive growth of IMC and the formation and growth of Kirkendall voids because they weaken the mechanical reliability of the joints. Therefore, in this study, isothermal aging evaluation of Cu pillar bump joints with a CS (Cu+ Sn-1.8Ag Solder) structure was performed and the corresponding results was reported.

• Journal of Chest Surgery
• /
• v.39 no.8 s.265
• /
• pp.573-578
• /
• 2006

Background: Generally hernia is diagnosed with simple chest or gastrointestinal x-ray. Sometimes CT or MRI can give lots of information for the diagnosis. However, there was no study for the differentiation with using CT findings between Morgagni hernia and pleuropericardial fat. The aim of this study was to evaluate the useful CT findings for differentiating Morgagni hernia from pleuropericardial fat. Material and Method: We retrospectively analyzed CT scans of eight patients with Morgagni hernia and 20 patients with abundant pleuropericardial fat without peridiaphragmatic lesions. All CT scans were performed with coverage of the whole diaphragm in the inspiration state. We evaluated 1) the presence of the defect of the anterior diaphragm, 2) the interface between the lung and fat, 3) the angle between the chest wall and fat, 4) the continuity between the extrapleural fat and fat, 5) the presence of the vessels within fat, and 6) the presence of a thin line surrounding fat. Result: In all cases with Morgagni hernia, the defect of the anterior diaphragm was seen. The interface was well-defined, smooth, and convex to the lung. The angle with the chest wall was acute. The continuity with the extrapleural fat was not seen. In the cases with abundant pleuropericardial fat, the defect of the anterior diaphragm was seen in three (15%). The interface was usually irregular (n=10) and flat (n=17). The angle with the chest wall was variable. The continuity with the extrapleural fat, that was markedly increased in amount, was usually seen (n=16). The thin line surrounding fat was seen in four cases with Morgagni hernia, however, not seen in all cases with pleuropericardial fat. All of the above findings were statistically significant, however, vessels within fat was not significant to differentiate Morgagni hernia (n=8/8) from pleuropericardial fat (n=14/20). Conclusion: The useful CT findings of Morgagni hernia were fatty mass with sharp margin, convexity toward lung, acute angle with chest wall, and thin line surrounding hernia. Branching structure within fatty mass representing omental vessels that has been known as a characteristic finding of Morgagni hernia was not useful for differentiating Morgagni hernia from pleuropericardial fat.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.8C
• /
• pp.1113-1124
• /
• 2004

In this paper, we proposed a hardware(H/W) structure which can compress and recontruct the input image in real time operation and implemented it into a FPGA platform using VHDL(VHSIC Hardware Description Language). All the image processing element to process both compression and reconstruction in a FPGA were considered each of them was mapped into H/W with the efficient structure for FPGA. We used the DWT(discrete wavelet transform) which transforms the data from spatial domain to the frequency domain, because use considered the motion JPEG2000 as the application. The implemented H/W is separated to both the data path part and the control part. The data path part consisted of the image processing blocks and the data processing blocks. The image processing blocks consisted of the DWT Kernel fur the filtering by DWT, Quantizer/Huffman Encoder, Inverse Adder/Buffer for adding the low frequency coefficient to the high frequency one in the inverse DWT operation, and Huffman Decoder. Also there existed the interface blocks for communicating with the external application environments and the timing blocks for buffering between the internal blocks The global operations of the designed H/W are the image compression and the reconstruction, and it is operated by the unit of a field synchronized with the A/D converter. The implemented H/W used the 69%(16980) LAB(Logic Array Block) and 9%(28352) ESB(Embedded System Block) in the APEX20KC EP20K600CB652-7 FPGA chip of ALTERA, and stably operated in the 70MHz clock frequency. So we verified the real time operation of 60 fields/sec(30 frames/sec).

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.23 no.6
• /
• pp.265-271
• /
• 2013

Czochralski (CZ) growth process is one of the most important techniques for growing high quality sapphire single crystal for LED application. In this study, the inductively-heated CZ growth processes for the sapphire crystal of 300 mm length have been analyzed numerically using finite element method. The hot zone structures were modified with the crucible geometry change and the additional insulation layer installed above the crucible. The results show that the solid-liquid interface height decreased from about 80 mm at initial stage to 40 mm after mid-stage due to achieve the growth speed balance. Also the optimal input power of the modified system was similar with the original one due to the compensation effects of the crucible geometry and additional insulation. The crystal temperature grown by the modified CZ grower was increased about 10 K than the original one. Therefore the sapphire crystal of 300 mm height was grown successfully.

• The Journal of Korean Academy of Prosthodontics
• /
• v.35 no.1
• /
• pp.43-66
• /
• 1997

Dental implant may be immediately placed in postextraction socket which has alveolar bone defect. The purpose of this study was to compare the bone regeneration and bone quality around defects adjacent to implants that were placed into extraction sockets according to EFEB, GTAM barrier and GTAM barrier with DFDB. Mandibular P2, P3 and P4 were extracted bilaterally in dogs, and buccal defects were created about 4mm in depth and 3.3mm in width. Screwed pure titanium implants, 3.8mm in diameter and 10mm in length, were placed into the extraction sockets. The experimental groups were divided into four groups : the G group was covered with a GTAM barrier on the defective area, the D+G group was filled with DFEB and covered with a GTAM barrier, the D group was filled with DFDB only and the control group was sutured without any special treatment on the defective area. The experimental animals were killed after 12 weeks and specimens were prepared for light microscopic evaluation and fluorescent dyes were administered daily for 2 weeks after implantation, and injected on the 4th and 11th week for fluorescent microscopic examination to observe new bone formation and bone remodeling. The new Bone height of the buccal defect was measured and compared with the another for bone gain and the removal torque for the implant was measured for the comparison of bone density and bone-implant osseointegration. Results obtained were as follows : 1. Experimental groups showed bone regeneration in oder from D+G, G, D group and control. D+G and G group was significantly from D group and control(P<0.01). 2. In the defective area of control the regenerated alveolar bone showed poorly developed lamellated structure and fibrous tissue intervention into the bone-implant interface but the others showed well developed lamellated structure and osseointegration. 3. All implant groups showed no significaant difference in the removal torque for implant(P>0.05) These results suggest that immediate implants placed in defective sockets were successfully osseointegrated and utilizing placed in defective sockets were successfully osseointegrated and utilizing not only the combination of GTAM and DFDB but also only the GTAM was favorable for the predictable regeneration of the defective area.

• The Journal of Korean Institute for Practical Engineering Education
• /
• v.3 no.2
• /
• pp.18-26
• /
• 2011

Computational chemistry is one of the chemistry fields that deals with the theoretical chemistry problem using computer calculations and can be described as the chemistry lab moved on computer space. In line with recent enhancement of processing capability of computers, utilization of high performance computer cannot be overemphasized in the field of computational chemistry in performing complex calculation of huge molecular structure and simulation. While they have to use commands and consoles for high performance computer to execute complex calculation of huge molecular structure and simulation, most of students in natural science and engineering, who are not experts in computer technically, are likely to be unaware of UNIX. Under the circumstances, web-based educational support system for computational chemistry is needed to enable them to practice computational chemistry, even not knowing UNIX command. In this study, e-Chem, one of such educational support systems, is developed by using Liferay portal platform, which is a Java open source more oriented to standard and outstanding in its content management and collaboration function than other web portals. By using this system, even students who are not familiar with computer, are expected to take part in lab classes and save time learning Unix command and also enhance the learning efficiency by using familiar interface.

• Progress in Medical Physics
• /
• v.20 no.2
• /
• pp.51-61
• /
• 2009

A Compton camera, which is based on the geometrical interpretation of Compton scattering, is a very promising gamma-ray imaging device considering its several advantages over the conventional gamma-ray imaging devices: high imaging sensitivity, 3-D imaging capability from a fixed position, multi-tracing functionality, and almost no limitation in photon energy. In the present study, a Monte Carlo-based, user-friendly Compton imaging simulator was developed in the form of a graphical user interface (GUI) based on Geant4 and $MATLAB^{TM}$. The simulator was tested against the experimental result of the double-scattering Compton camera, which is under development at Hanyang University in Korea. The imaging resolution of the simulated Compton image well agreed with that of the measured image. The imaging sensitivity of the measured data was 2~3 times higher than that of the simulated data, which is due to the fact that the measured data contains the random coincidence events. The performance of a stacking-structure type Compton camera was evaluated by using the simulator. The result shows that the Compton camera shows its highest performance when it uses 4 layers of scatterer detectors.

• Journal of KIISE
• /
• v.41 no.9
• /
• pp.652-665
• /
• 2014

Many important terminologies in biomedical text are expressed as abbreviations or acronyms. We newly suggest a semantic link topic model based on the concepts of topic and dependency link to disambiguate biomedical abbreviations and cluster long form variants of abbreviations which refer to the same senses. This model is a generative model inspired by the latent Dirichlet allocation (LDA) topic model, in which each document is viewed as a mixture of topics, with each topic characterized by a distribution over words. Thus, words of a document are generated from a hidden topic structure of a document and the topic structure is inferred from observable word sequences of document collections. In this study, we allow two distinct word generation to incorporate semantic dependencies between words, particularly between expansions (long forms) of abbreviations and their sentential co-occurring words. Besides topic information, the semantic dependency between words is defined as a link and a new random parameter for the link presence is assigned to each word. As a result, the most probable expansions with respect to abbreviations of a given abstract are decided by word-topic distribution, document-topic distribution, and word-link distribution estimated from document collection though the semantic dependency link topic model. The abstracts retrieved from the MEDLINE Entrez interface by the query relating 22 abbreviations and their 186 expansions were used as a data set. The link topic model correctly predicted expansions of abbreviations with the accuracy of 98.30%.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.05a
• /
• pp.8.1-8.1
• /
• 2011

Nanocrystalline titanium dioxide ($TiO_2$) materials have been widely used as an electron collector in DSSC. This is required to have an extremely high porosity and surface area such that the dye can be sufficiently adsorbed and be electronically interconnected, resulting in the generation of a high photocurrent within cells. In particular, their geometrical structures and crystalline phase have been extensively investigated as important issues in improving its photovoltaic efficiency. In this study, we present a new strategy to fabricate a photoelectrode having a periodic structured $TiO_2$ film templated from 1D or 3D polystyrene (PS) microspheres array. Monodisperse PS spheres of various radiuses were used for colloidal array on FTO glasses and two types of photoelectrode structures with different $TiO_2$ materials were investigated respectively. One is the igloo-shaped electrode prepared by $TiO_2$ deposition by RF-sputtering onto 2D microsphere-templated substrates. At the interface between the film and substrate, there are voids formed by the decomposition of PS microspheres during the calcination step. These holes might be expected to play the predominant roles as scattering spherical voids to promote a light harvesting effect, a spacious structure for electrolytes with higher viscosity and effective paths for electron transfer. Additionally the nanocrystalline $TiO_2$ phase prepared by the RF-sputtering method was previously reported to improve the electron drift mobility within $TiO_2$ electrodes. This yields solar cells with a cell efficiency of 2.45% or more at AM 1.5 illumination, which is a very remarkable result, considering its $TiO_2$ electrode thickness (<2 ${\mu}m$). This study can be expanded to obtain higher cell efficiency by higher dye loading through the increase of surface area or multi-layered stacking. The other is the inverse opal photonic crystal electrode prepared by titania particles infusion within 3D colloidal arrays. To obtain the enlargement of ordered area and high quality of crystallinity, the synthesis of titania particles coated with a organic thin layer were applied instead of sol-gel process using the $TiO_2$ precursors. They were dispersed so well in most solvents without aggregates and infused successfully within colloidal array structures. This ordered mesoporous structure provides the large surface area leading to the enough adsorption of dye molecules and have an light harvesting effect due to the photonic band gap properties (back-and-forth reflection effects within structures). A major advantage of this colloidal array template method is that the pore size and its distribution within $TiO_2$ photoelectrodes are determined by those of latex beads, which can be controlled easily. These materials may have promising potentials for future applications of membrane, sensor and so on as well as solar cells.

• Korean Journal of Materials Research
• /
• v.11 no.8
• /
• pp.671-678
• /
• 2001

All solid-state thin film micro supercapacitor, which consists of $RuO_2$/LiPON/$RuO_2$ multi layer structure, was fabricated on Pt/Ti/Si substrate using a $RuO_2$ electrode. Bottom $RuO_2$ electrode was grown by dc reactive sputtering system with increasing $O_2/[Ar+O_2]$ ratio at room temperature, and a LiPON electrolyte film was subsequently deposited on the bottom $RuO_2$ electrode at pure nitrogen ambient by rf reactive sputtering system. Room temperature charge-discharge measurements based on a symmetric $RuO_2$/LiPON/$RuO_2$ structure clearly demonstrates the cyclibility dependence on the microstructure of the $RuO_2$ electrode. Using both glancing angle x-ray diffraction (GXRD) and transmission electron microscopy (TEM) analysis, it was found that the microstructure of the $RuO_2$ electrode was dependent on the oxygen flow ratio. In addition, x- ray photoelectron spectroscopy(XPS) examination shows that the Ru-O binding energy is affected by increasing oxygen flow ratio. Furthermore, TEM and AES depth profile analysis after cycling demonstrates that the interface layer formed by interfacial reaction between LiPON and $RuO_2$ act as a main factor in the degradation of the cyclibility of the thin film micro-supercapacitor.