• Journal of Sensor Science and Technology
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• v.12 no.2
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• pp.72-78
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• 2003

To observe the effect of excitation coil pitch on the micro fluxgate magnetic sensor, two sensors are fabricated using multi layer board process and the pitch distance of excitation coil are $260\;{\mu}m$ and $520\;{\mu}m$, respectively. The fluxgate sensor consists of five PCB stack layers including one layer of magnetic core and four layers of excitation and pick-up coils. The center layer as magnetic core is made of a Co-based amorphous magnetic ribbon with extremely high DC permeability of ${\sim}100,000$ and has a rectangular-ring shape to minimize the magnetic flux leakage. Four outer layers as excitation and pick-up coils have a planar solenoid structure and are made of copper foil. In case of the fluxgate sensor having the excitation coil pitch of $260\;{\mu}m$, excellent linear response over the range of $-100\;{\mu}T$ to $+100\;{\mu}T$ is obtained with sensitivity of 780 V/T at excitation sine wave of $3V_{p_p}$ and 360 kHz. The chip size of the fabricated sensing element is $7.3\;{\times}\;5.7\;mm^2$. The very low power consumption of ${\sim}8\;mW$ is measured. This magnetic sensor is very useful for various applications such as: portable navigation systems, telematics, VR game and so on.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.09a
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• pp.183-192
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• 2001

1- Buildup PCB technology is utilized to a bare chip attach substrate technology for packaging of semiconductor chip 2- Requirement for the substrate design rule is described in SIA International Technology Roadmap for Semiconductor. 3- There are seven fabrication methods of build-up technology. 4- Coating and lamination for resin and photo, and laser for micro via hope processes are available. Below $50\mu\textrm{m}$ in diameter is possible. 5- Fine pitch lines down to $30\mu\textrm{m}$ can be achieved by pattern plating with better electrical property. 6- Dielectric loss reduction is a key material improvement item for next generation build-up technology. 7- High band width up to 512 GB/s is possible with current wiring groundrule.

• Journal of Industrial Technology
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• v.14
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• pp.39-48
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• 1994

Up to the present the study on the performance prediction of HAWT was perfomed mainly by assuming the axial flow. So in this paper we aimed at the fully non-axial flow of HAWT. For this purpose, we defined the wind turbine pitch angle in addition to the yaw angle to specify the arbitrary wind direction. And we adopted the Glauert method as the basic analysis method then modified this method suitably for our goal. By comparing the computational results obtained by this modified new Glaurert method with the experimental results, it was proved that our method was a very efficient method.

• Proceedings of the KSPS conference
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• 1997.07a
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• pp.228-229
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• 1997

1 Intonation is important. It cannot be ignored. To convince students of the importance of intonation, we can use sentences with two very different interpretations according to intonation. Example: "I thought it would rain" with a fallon "rain" means it did not rain, but with a fall on "thought" and a rise on "rain" it means that it did rain. 2 Although complex, intonation is structured. For both teacher and student, the big job of tackling intonation is made simpler by remembering that intonation can be analysed into systems and units. There are three main systems in English intonation: Tonality (division into phrases) Tonicity (selection of accented syllables) Tone (the choice of pitch movements) Examples: Tonality: My brother who lives in London is a doctor. Tonicity: Hello. How ARE you. Hello. How are YOU. Tone: Ways to say "Thank you" 3 In deciding what to teach, we must distinguish what is universal from what is specifically English. This is where contrastive studies of intonation are very valuable. Usually, for instance, division into phrases (tonality) works in broadly similar ways across languages. Some uses of pitch are also similar across languages - for example, very high pitch may signal excitement or urgency. 4 Although most people think that intonation is mainly about pitch (the tone system), actually accent placement (tonicity) is probably the single most important aspect of English intonation. This is because it is connected with information focus, and the effects on interpretation are very clear-cut. Example: They asked for coffee, so I made them coffee. (The second occurrence of "coffee" must not be accented). 5 Ear-training is the beginning of intonation training in the VeL approach. First, students learn to identify fall vs rise vs fall-rise. To begin with, single words are used, then phrases and sentences. When learning tones, the fIrst words used should have unstressed syllables after the stressed syllable (Saturday) to make the pitch movement clearer. 6 In production drills, the fIrst thing is to establish simple neutral patterns. There should be no drama or really special meanings. Simple drills can be used to teach important patterns: Example: A: Peter likes football B: Yes JOHN likes football TOO A: Mary rides a bike B: Yes JENny rides a bike TOO 7 The teacher must be systematic and let learners KNOW what they are learning. It is no good using new patterns and hoping that students will "pick them up" without noticing. 8 Visual feedback of fundamental frequency with a computer display can help students learn correct patterns. The teacher can use the display to demonstrate patterns, or students can practise by themselves, imitating recorded models.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.830-837
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• 2016

In order to improve the compressive strength of graphite foams (GFms), mesophase pitch (MP) was stabilized in air atmosphere and then fluorinated at different conditions. The Fluorine/Carbon (F/C) in surface-chemical contents of fluorinated MP has range of 23.75%~61.48% according to the different fluorine partial pressure. The compressive strengths of GFms prepared from fluorinated MP were increased in proportion to the apparent densities. The compressive strength of the GFm produced from MP with 35.93% of F/C (%) showed maximum value in $2.93{\pm}0.06MPa$, which was increased up to 27.95% than that of the GFm prepared from un-fluorinated MP. This result was attributed that the interface bonding between of MPs due to fluorine functional groups with high surface energy helped to improve compressive strength of the GFm.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.2 s.39
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• pp.21-26
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• 2006

We developed a bonding at low temperature using fine pitch Sn and In bumps, and studied the reliability of the fine pitch In-Sn solder joints. The $30{\mu}m$ pitch Sn and In bumps were joined together at $120^{\circ}C$. A non conductive adhesive (NCA) was applied during solder joining. Thermal cycling test ($0^{\circ}C-100^{\circ}C$, 2 cycles/h) of up to 2000 cycles was carried out to evaluate the reliability of the solder joints. The bondability was evaluated by measuring the contact resistance (Rc) of the joints through the four point probe method. As the content of filler increased, the reliability improved in the solder joints during thermal cycling test because the contact resistance increased little. The filler redistributed the stress and strains from the thermal shock over the entire joint area.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.1
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• pp.96-107
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• 1996

A voice personality transformation algorithm using orthogonal vector space conversion is proposed in this paper. Voice personality transformation is the process of changing one person's acoustic features (source) to those of another person (target). In this paper, personality transformation is achieved by changing the LPC cepstrum coefficients, excitation spectrum and pitch contour. An orthogonal vector space conversion technique is proposed to transform the LPC cepstrum coefficients. The LPC cepstrum transformation is implemented by principle component decomposition by applying the Karhunen-Loeve transformation and minimum mean-square error coordinate transformation(MSECT). Additionally, we propose a pitch contour modification method to transform the prosodic characteristics of any speaker. To do this, reference pitch patterns for source and target speaker are firstly built up, and speaker's one. The experimental results show the effectiveness of the proposed algorithm in both subjective and objective evaluations.

• Tribology and Lubricants
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• v.32 no.4
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• pp.119-124
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• 2016

In the sapphire wafering process, lapping is a crucial operation in order to reduce the damaged layer and achieve the target thickness. Many parameters, such as pressure, velocity, abrasive, slurry and plate, affect lapping characteristics. This paper presents an experimental investigation on the effect of the plate groove on the material removal rate and roughness of the wafer. We select the spiral pattern and rectangular type as the groove shapes. We vary the groove density by controlling the groove shape dimension, i.e., the groove width and pitch. As the groove density increases to 0.4, the material removal rate increases and gradually reaches a saturation point. When the groove density is low, the pressing load is mostly supported by the thick film, and only a small amount acts on the abrasives resulting to a low material removal rate. The roughness decreases on increasing the groove density up to 0.3 because thick film makes partial participations of large abrasives which make deep scratches. From these results, we could conclude that the groove affects the contact condition between the wafer and plate. At the same groove density, the pitch has more influence on reducing the film thickness than the groove width. By decreasing the groove density with a smaller pitch and larger groove width, we could achieve a high material removal rate and low roughness. These results would be helpful in understanding the groove effects and determining the appropriate groove design.

• Wind and Structures
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• v.32 no.5
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• pp.471-485
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• 2021

Onshore wind turbines may experience substantially different wind loads depending on their working conditions, i.e. rotation velocity of rotor blades, incoming freestream wind velocity, pitch angle of rotor blades, and yaw angle of the wind-turbine tower. In the present study, aerodynamic loads acting on a horizontal axis wind turbine were accordingly quantified for the high tip speed ratio (TSR) at high yaw angles because these conditions have previously not been adequately addressed. This was analyzed experimentally on a small-scale wind-turbine model in a boundary layer wind tunnel. The wind-tunnel simulation of the neutrally stratified atmospheric boundary layer (ABL) developing above a flat terrain was generated using the Counihan approach. The ABL was simulated to achieve the conditions of a wind-turbine model operating in similar inflow conditions to those of a prototype wind turbine situated in the lower atmosphere, which is another important aspect of the present work. The ABL and wind-turbine simulation length scale factors were the same (S=300) in order to satisfy the Jensen similarity criterion. Aerodynamic loads experienced by the wind-turbine model subjected to the ABL simulation were studied based on the high frequency force balance (HFFB) measurements. Emphasis was put on the thrust force and the bending moment because these two load components have previously proven to be dominant compared to other load components. The results indicate several important findings. The loads were substantially higher for TSR=10 compared to TSR=5.6. In these conditions, a considerable load reduction was achieved by pitching the rotor blades. For the blade pitch angle at 90°, the loads were ten times lower than the loads of the rotating wind-turbine model. For the blade pitch angle at 12°, the loads were at 50% of the rotating wind-turbine model. The loads were reduced by up to 40% through the yawing of the wind-turbine model, which was observed both for the rotating and the parked wind-turbine model.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.3
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• pp.67-74
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• 2011

Keys to high wiring density semiconductor packages include flip-chip bonding and build-up substrate technologies. The current issues are the establishment of a fine pitch flip-chip bonding technology and a low coefficient of thermal expansion (CTE) substrate technology. In particular, electromigration and thermomigration in fine pitch flipchip joints have been recognized as a major reliability issue. In this paper, electromigration and thermomigration in Cu/Sn-3Ag-0.5Cu (SAC305)/Cu flip-chip joints and electromigration in Cu/In/Cu flip chip joints are investigated. In the electromigration test, a large electromigration void nucleation at the cathode, large growth of intermetallic compounds (IMCs) at the anode, a unique solder bump deformation towards the cathode, and the significantly prolonged electromigration lifetime with the underfill were observed in both types of joints. In addition, the effects of crystallographic orientation of Sn on electromigration were observed in the Cu/SAC305/Cu joints. In the thermomigration test, Cu dissolution was accelerated on the hot side, and formation of IMCs was enhanced on the cold side at a thermal gradient of about $60^{\circ}C$/cm, which was lower than previously reported. The rate of Cu atom migration was found comparable to that of electromigration under current conditions.