• Journal of the Microelectronics and Packaging Society
• /
• v.20 no.4
• /
• pp.59-63
• /
• 2013

In this paper, the impact of the copper densities of substrate layers on IC package warpage is studied experimentally and numerically. The substrate strips used in this study contained two metal layers, with the metal densities and patterns of these two layers varied to determine their impacts. Eight legs of substrate strips were prepared. Leg 1 to leg 5 were prepared with a HD (high density) type of strip and leg 6 to leg 8 were prepared with UHD (ultra high density) type of strip. The top copper metal layer was designed to feature meshed patterns and the bottom copper layer was designed to feature circular patterns. In order to consider the process factors, the warpage of the substrate bottom was measured step by step with the following manufacturing process: (a) bare substrate, (b) die attach, (c) applying mold compound (d) and post reflow. Furthermore, after the post reflow step, the substrate strips were diced to obtain unit packages and the warpage of the unit packages was measured to check the warpage trends and differences. The experimental results showed that the warpage trend is related to the copper densities. In addition to the experiments, a Finite Element Modeling (FEM) was used to simulate the warpage. The nonlinear material properties of mold compound, die attach, solder mask, and substrate core were included in the simulation. Through experiment and simulation, some observations were concluded.

• Archives of Plastic Surgery
• /
• v.38 no.1
• /
• pp.89-92
• /
• 2011

Purpose: Electrical burn of scalp is uncommon. Much more, chronically exposed dura in unstable burn scar is quite exceptional. Hence, we report a case of chronically exposed dura following electrical burn. Methods: A 63-year-old man presented with an about 40 years history of an ulcerative lesion arising from electrical burn scar with 'squeeze like sensation' around wound. Wound was about $6{\times}8$ cm. Area in the center was $3{\times}3$ cm nonviable dura without sequestrum. Tangential excision with an intraoperative neurosurgical consultation and transposition flap under general anesthesia was done. Intraoperative biopsy was done. The wound was diagnosed as chronic osteomyelitis, not Marjolin ulcer. Flap was taken successfully. But after 5 days, infectious discharge had been appeared during 2 weeks, despite irrigation and drainage. As flap was re-evaluated, we could see remnant necrotic dura. After that, latissimus dorsi muscle free flap with meshed split thickness skin graft was transferred without excision of necrotic dura. Results: Flap was taken successfully. Follow-up at 10 weeks has been uneventful, with good and stable coverage of the wound. Conclusion: It is true that complete excision of devitalized tissue with sagittal sinus obliteration is prerequisite to flap taken. But necrotic dura was tangentially excised instead of total dura excision, because, posterior two-thirds of the sagittal sinus was involved underneath. Muscle is rich in blood vessels and decrease the recipient-site bacterial count effectively. In this case, muscle flap with skin graft without total dura excision is an alternative treatment.

• The Journal of the Korea Contents Association
• /
• v.12 no.1
• /
• pp.146-153
• /
• 2012

This study conducted content analysis for the 266 public access programs. By doing so it aimed to suggest ideal directions for the pubic access. This study found that most programs were well meshed with variety, locality, and representation of minorities, which are goals of what public access programs are for. However, this study suggested that more diverse producers in terms of ages and occupations need to participate and also cable SOs should try to motivate viewers by covering various topics and areas in public access programs in the future. Lastly, the Korea Communications Commission also need to continuously offer more positive financial aids and public relations to support this program.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.12 no.1
• /
• pp.1-12
• /
• 2016

The current economic crisis is making new demands on manufacturing industry, in particular, in terms of the flexibility and efficiency of production processes. This requires production and administrative processes to be meshed with each other by means of IT systems to optimise the use and capacity utilisation of machines and lines but also to be able to respond rapidly to wrong developments in production and thus to minimise adverse impacts on the business. The future scenario of the "smart factory" represents the zenith of this development. The factory can be modified and expanded at will, combines all components from different manufacturers and enables them to take on context-related tasks autonomously. Integrated user interfaces will still be required at most for basic functionalities. The complex control operations will run wirelessly and ad hoc via mobile terminals such as PDAs or smartphones. The comnination of IoT, and Big Data optimisation is bringing about huge opportunities. these processes are not just limited to manufacturing, anywhere a supply chain environment exists can benefit from information provided by linked devices and access to big data to inform their decision support. Building a smart factory with smart assets at its core means reaching those desired new levels of productivity and efficiency. It means smart products that leverage advanced traceability, connectivity and intelligence. For businesses, it means being able to address the talent crunch through more autonomous. In a Smart Factory, machinery and equipment will have the ability to improve processes through self-optimization and autonomous decision-making.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.10 no.5
• /
• pp.713-723
• /
• 1986

The purpose of this research was to study the heat transfer characteristics of heat pipe which used non-metallic(SiO$_{2}$), circumferential wick and meshed slab wick as ADI method and experimental results. Compared wick experimental data and results by ADI method showed the good agreement and ADI method was utilized in pridicting the performance of heat pipe. Also, ADI method was applied to predict heat pipe performance according to the various volume ratios of metallic bond. The heat transfer characteristics of heat pipe could be predicted by heat flux and superheat term below the maximum heat flux limit. According to the addition ratio of metallic bond, heat transfer ratio could be improved as 2-3 times and when heat conductivity ratio(K$_{b}$/K$_{a}$) was increased at 4-12 ratio, heat transfer was in creased as 1.7-2.4 times, and the prediction of heat transfer could be show as exponential type. In producting non-metallic wick used to low heat pipe, metallic bond which is the conductivity of good quality and enduring for high temperature will be improved as in important problem.

• Archives of Plastic Surgery
• /
• v.35 no.4
• /
• pp.487-490
• /
• 2008

Purpose: The latissimus dorsi flap and the serratus anterior flap have been used as combined flaps to reconstruct extensive defects. Because these two muscles are usually supplied by the subscapular-thoracodorsal vessels, the two flaps can be based on vascular pedicle that is long and anatomically reliable. In this case, we reported that serratus anterior possessed an anomalous arterial supply totally independent from the subscapular pedicle while raising combined latissimus dorsi and serratus anterior flap. Methods: A 35-year-old male with extensive soft tissue defect in the left perineum and thigh visited. Muscle defects of the medial thigh were observed, and femoral nerve and vessels were exposed. Combined latissimus dorsi and serratus anterior free flap was raised to reconstruct defect. On raising flaps, artery supplying the serratus anterior muscle originated from the axillary artery directly, was lying on the undersurface of the serratus anterior muscle. Results: Because two flap pedicles had no communication and latissimus dorsi muscle was large enough to cover soft tissue defect, we transferred only latissimus dorsi free flap with 1 : 3 meshed skin graft. Patient had limb salvage and satisfactory functional outcome. Conclusion: There are many variations of arterial pedicles of flaps. However, most of these variations remain within known anatomical consistence, thus is an indicator in planning the dissection of the vessels. According to documents, arterial pedicle to the serratus muscle not originated from the thoracodorsal artery is rarely reported, and in most of these cases, the arteries are originated from the subscapular artery. Thus pedicle directly originated from the axillary artery to serratus muscle is a very rare variation in its vascular anatomy.

• Journal of Fashion Business
• /
• v.5 no.4
• /
• pp.14-26
• /
• 2001

A lot of designers are adopting a mixed imitation as techniques of cretion because cultural boundary and structure of meaning in the era of post-modernism are collapsed and dissolved. I raise up a question mark to how can genuine and creative designers can be identified at this epoch when we are today familiar with the trend of informationalization, opening and globalization. Characterisitics of multi-culturalism and compromising blending are meshed with appearance of a theory of disorganization and consumer-driven economic activity of multi-national enterprises in the age of post capitalism. Accordingly it can be said that designers are leaning upon public and consumeroriented pattern rather than pursuing a creative cultural production. With mass media in rapid advancement and public culture in father dissemination, mass production and mass re-production became a natural cultural phenomenon strengthen ing its root. Creative designers somewhat slow and limitative in pace of adaption to rapid changing society amid such social backgrounds and flooded information are coming to dead-end of wall. A mixed imitation as techniques of creation is a result of borrowing, duplicating or re-combining of existing things because the mixed imitation is equivalent to borrowing, copying, compilation and recombination of well-known artworks, motive, diverse people's cultural features, image, techniques and the likes. It is too delicate thing for one to definitely distinguish such cultural phenomenon from either one as creative work or a plagiarized work. Looking into the facts as they are, we should recognize the designers limitation in their creative works by means of the mixed imitation. thus we can have a view upon them from a criticizing standpoint against the designers creation and imitation. On the other hand, when we look at things how the mixed imitation appears in the fashion as a piece of culture, we can understand something of the contemporary designers. I try to find a significance in seeking out a method of approaching to creative fashion designers direction in future times.

• Archives of Reconstructive Microsurgery
• /
• v.25 no.2
• /
• pp.29-36
• /
• 2016

Purpose: Skin grafting is used for the transfer of cutaneous tissue from one site of the body to another. To improve graft survival, close contact between the graft and the wound bed is essential for vessels to grow across the gap. Here, we introduce an easy and efficient dressing method to improve graft survival. Materials and Methods: A retrospective chart review was performed to identify patients who underwent split thickness skin graft and negative pressure wound therapy (NPWT) or conventional treatment between January 2007 and April 2015. Overall, 25 consecutive patients were included in the NPWT group and 49 were included in the conventional dressing group to compare the outcome of the procedure. The data were obtained from medical records, including age, sex, cause of the skin defect, size of graft, time for healing, wound preparation time, and complications. Results: Of the NPWT group, the average wound size was $147.04{\pm}146.74cm^2$ (range, $9{\sim}900cm^2$). With the exception of one patient, all wounds healed without the need for further procedure. The average duration of time required for the NPWT group, which was defined as removal of stitches (or staples) and no need for additional active dressing, was $6.4{\pm}1.97days$ (range, 5~15 days). The average time for the conventional dressing group was $10.78{\pm}2.38days$ (range, 5~15 days). Conclusion: NPWT can be used to cover regions in which wound healing does not occur fully or when neither tie-over nor compressive dressings are applicable. This treatment also reduced wound healing time and allowed earlier patient mobilization and hospital discharge.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.6B
• /
• pp.977-983
• /
• 2010

In mobile and secure military networks, full-meshed IPSec tunnels, which do correspond to not physical links but logical links between each IPSec device and its peer, are required to provide multicast communications. All IPSec devices need support in changing IPSec tunnels by a way of using a multicast group key which is updated dynamically. Tactical terminals, which often constitute a group, need also secure multicast communications in the same group members. Then, the multicast group key is required to be updated dynamically in order to support group members' mobility. This paper presents challenging issues of designing a secure and dynamic group key management of which concept is based on the Diffie-Hellman (DH) key exchange algorithm and key trees. The advantage of our dynamic tree based key management is that it enables the dynamic group members to periodically receive status information from every peer members and effectively update a group key based on dynamically changing environments.

• Tribology and Lubricants
• /
• v.32 no.3
• /
• pp.101-105
• /
• 2016

Trap effect of groove is evaluated in a lubricating system using computational fluid dynamics (CFD) analysis. The simulation is based on the standard k-ε turbulence model and the discrete phase model (DPM) using a commercial CFD code FLUENT. The simulation results are also capable of showing the particle trajectories in flow field. Computational domain is meshed using the GAMBIT pre-processor. The various grooves are applied in order to improve lubrication characteristics such as reduction of friction loss, increase in load carrying capacity, and trapping of the wear particles. Trap effect of groove is investigated with variations in cross-sectional shape and Reynolds number in this research. Various cross-sectional shapes of groove (rectangular, triangle, U shaped, trapezoid, elliptical shapes) are considered to evaluate the trap effect in simplified two-dimensional sliding bearing. The particles are assumed to steel, and defined a single particle injection condition in various positions. The “reflect” boundary condition for discrete phase is applied to the wall boundary, and the “escape” boundary condition to “pressure inlet” and “pressure outlet” conditions. The streamlines are compared with particles trajectories in the groove. From the results of numerical analysis in the study, it is found that the cross-sectional shapes favorable to the creation of vortex and small eddy current are effective in terms of particle trapping effect. Moreover, it is found that the Reynolds number has a strong influence on the pattern of vortex or small eddy current in the groove, and that the pattern of the vortex or small eddy current affects the trap effect of the groove.