Swinging Higher and More Safely: A Mathematical ModelAhn Seonmin

Swinging on swings is one of the classic activities enjoyed by people all over the world. While people swing back and forth automatically, there exist techniques to make one swing higher. We found the optimal method by mathematical modeling. We started off with a model of a simple pendulum and analyzed its motion. We examined 4 realistic methods to swing and concluded that the most efficient method is to pump vigorously after passing the lowest point. We also proposed a safe swing which does not allow one to swing too high. If a swing is propelled excessively and goes too high, it is dangerous. This can be prevented by controlling the damping ratio of a swing. We substituted several damping ratios to our swing model, and found that 0.193 is a safe damping ratio. We used Newton's laws to establish the governing equation for the swing model and considered changes in energy to find the optimal point to start pumping.

A Hybrid Analytical Modeling Method for Signal Via Transition Traces in Multi-Layer PCB's J

Yoo Jeongsik

As multiple chips are being integrated into a single package with increased operation frequency, switching noise coupling on power, ground plane have become an important design issue. To reduce the noise coupling, ‘split power plane’ and ‘electromagnetic bandgap (EBG)’ structures have been generally used in package substrates having substrates multilayered power and ground planes. Consequently, there is an increasing need for an efficient method to analyze a split power ground plane in a multilayered package. This paper introduces a hybrid analytical modeling method for characterizing the split power, ground plane and especially about signal via transition trace in a multilayer package. The proposed method uses a resonant cavity model combined with a segmentation method. To verify the proposed method, multilayered test package are fabricated and tested by means of frequency domain measurements. In addition, an optimal power, ground plane design method was successfully demonstrated for suppressing noise coupling between chips on a single package.

Electromagnetic Band Gap Structure for the Stabilization of Chip Operation ... Chulsoon Hwang

Electromagnetic Band Gap Structure for the Stabilization of Chip Operation in Mobile Devices

The signal via is heavily used in both high-density System-in-Package (SiP)’s and printed circuit board(PCB).’s Furthermore, power ground plane used for low impedance of power distribution network causes cavity noise the caused cavity noise is coupled through the signal via when reference plane of the signal via is exchanged. The coupled cavity noise degrades transition signal quality. In multi-layer board, the high frequency cavity noise is inevitable to reference plane change via . In this paper, reference plane change via analysis in electromagnetic band-gap (EBG) structure is made. EBG structures are used to make ensure return current path of reference plane change via. With ring structure, the mushroom type EBG is used to prevent cavity noise coupling into signal via by suppression cavity resonance near signal via. It is shown that, within the stop band, return current path of via in EBG structure is free from cavity resonance noise. In the presence of EBG structures and slot in power plane, the voltage noise and timing jitter are significantly reduced for random noise source.

Oxide Thin-Film Transistors: Introduction and a Review of Recent Advances

Namho Jeon

In this paper I review recent progress made in the area of materials, fabrication processes, device designs, and applications related to oxide thin-film transistors(TFTs), with an emphasis on papers published during last decade. Oxide semiconducting materials were first used as a active layer of TFTs in 1995 and there are exact properties of them and operating mechanisms as a active material of TFTs since history of them is quite short. Some earlier papers that played an important role in shaping the oxide TFT field are included, and a number of previously published review papers that cover that early period more completely are referenced. Markets are requires ultimate optoelectronics and displays with low cost, transparent and flexible TFT devices. It is forecasted that oxide TFTs lead new explosive growth in the next generation of display. Oxide TFTs have a lot of beauty points to realize the ultimate optoelectronics and displays but still have many challenges to overcome. New values of oxide TFTs can generate new applications.

Development of A Capacity-Filtering Method for Medium-term Scheduling of Semiconductor Fab

Seong KyungChan
The operational management of an electronics Fab such as semiconductor Fab, LCD Fab or PCB Fab requires long-term planning, medium-term scheduling and short-term control. Among the three areas, the weakest link is the medium-term scheduling or finite-capacity planning area which is responsible for generating mid-term schedule or finite-capacity plans. In such an electronic Fab, medium-term schedules such as release plan production plans are critical in achieving the goal of full capacity and on-time production. However, existing finite capacity planning methods, including time-bucking and time-shifted POR approachs which are most widely employed, are not able to accommodate the capacity fluctuations that can arise in the electronics Fab, especially the semiconductor Fab. In most semiconductor Fabs, there are workstations that are near-bottleneck, any of which may become a bottleneck at a given points in time due to changing product mixes and unexpected down time. Managing the interactions between these near-bottleneck stations to maintain high throughput and on-time delivery performance is a very challenging task. This is why existing finite capacity methods have difficulty planning and scheduling in semiconductor Fab. As other theoretical approaches also have shortcomings, it is anticipated at present that the capacity-filtering method proposed in this thesis is a viable solution.The comparative performance analysis of a real semiconductor Fab demonstrates that the proposed capacity-filtering method is superior to the existing ‘time-bucketing’ and ‘time-shifted POR’ methods. While a major drawback of this approach is that the fixed-size time-buckets do not adequately reflect the actual line capacity, the proposed method is able to be flexible enough to permit quick replanning. In addition they are able to produce high-quality production plans. This is one of reason why the proposed method is better than the others. What in more, this thesis represents a possibility that it can be used in ‘real-life’ release planning and Fab-out (production) planning.

Checking Errors Using Event Logs: A Report Kim TaeDong

There are many processes in the world open to fraud and audit principles are developed to prevent them. While a lot of research has been conducted with respect to the application of these principles to the process of fraud protection / prevention, most of it has related to the design process. As a result while they can check the process design model, if people violate them when the process executes, they can’t be checked. In this paper we suggest checking principles using event logs in order to catch runtime violations and previous records. To use event logs for checking principles, we define an event log with document information and logic using the event log definition. We use an accounting process as an example process, and then we evaluate the logic. In that evaluation, we insert violation not in the model but in the event log and the logic almost catches the violation.

Coherent X-ray Source Development by Manipulating Atoms in a Super-Intense Femtosecond Laser Field

Yun Hyeok

From the development of super-intense and ultrafast laser fields, strong field phenomena came into being newly in atomic physics related to optics. One phenomena related to strong field effect, which is used to generate coherent X-ray, is high harmonic generation. High harmonic waves are generated by repeated modulation of electron orbit around nucleus by intense laser field. Coherent X-ray, one of high harmonic waves, gives rise to a new era of extreme science in space and time; nano-metrology and atto-physics.