• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.5
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• pp.329-333
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• 2012

For phase transition method, good record sensitivity, low heat radiation, fast crystallization and hi-resolution are essential. Also, a retention time is very important part for phase-transition. In our past papers, we chose composition of $Ge_1Se_1Te_2$ material to use a Se factor which has good optical sensitivity than conventional Sb. Sb/Ge-Se-Te thin films are fabricated and irradiated with UV light source to investigate a reversible phase change by Sb-doped condition. Because of Sb atoms, the Sb inserted sample showed better performance than conventional one. We should note that this novel one showed another possibility for phase-change random access memory.

• Journal of Ocean Engineering and Technology
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• v.9 no.1
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• pp.101-110
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• 1995

In SMA(Shape Memory Alloy), the degradation by fatigue is one of the most important problems to be overcome, when SMA is used for robot-actuator materials. The actuator is operated repetitively for long time and its repeating operation develops the fatigue degradation of SMA. The fatigue degradation changes the transformation temperature and deformation behavior and results in inaccurate operation and deformation which results form repeating operation is to be investigated in advance and the scheme to resolve those problems have to be made for the design of actuator. In this paper, for the improvement of the fatigue degradation by repetive movement and better control of the correct movement by the stability of martensite transformation in the development of Robots actuator, Pre-strain(0, 1.5, 5, 8%) are loaded in the specimens and fatigue testing were carried out by the method of heating and cooling in direct condition. From the results of these experiments, the effect on pre-strain which affect the transformation characteristic and fatigue degradation phenomena were correctly investigated.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.3
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• pp.149-157
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• 2017

In this paper, we propose BCMR (Block Classification with Monitor and Restriction) to ensure the isolation and to reduce the interference of blocks between a garbage collection and a wear leveling. The proposed BCMR monitors an endurance variation of blocks during the garbage collection and detects hot blocks by making a restriction condition based on this information. The proposal induces a block classification by its update frequency for the garbage collection and the wear leveling, so we will get a prolonged lifetime of NAND flash memory systems. In a performance evaluation, BCMR prolonged the lifetime of NAND flash memory systems by 3.95%, on average and reduced a standard deviation per block by 7.4%, on average.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.7
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• pp.43-49
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• 2000

We proposed ADD(Alternate Directional Delay) circuit technique as the DLL(Delay Locked Loop) circuits which technique is established the data valid window(tDV) in DDR(Double Data Rate) Synchronous DRAM. This technique could be decrease area-overhead which it could generated bidirectional clock simultaneously using only one delay chain block. In this paper for high speed memory with relatively small size. This technique decreased area-overhead more 2 times than SMD(Synchronous Mirror Delay) technique. ADD technique has 50ps-140ps jitter and the operation frequency has 166MHz-66MHz range.(at 2.5V, TYP. condition)

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.562-567
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• 2016

Morphing wing which has a configuration optimized to flight speed and condition is faced to a lot of barriers to be overcome such as actuator technique, structural mechanization technique, flexible skin material, control law, and so on. As the first step for developing a morphing wing with rapid response, we designed and fabricated the morphing airfoil using a SMA(shape memory alloy) wire actuator and torsional bias springs. The design concept of the morphing airfoil was verified through operation test. The measured results show that the flap deflects smoothly and fast.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.1
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• pp.77-86
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• 2004

This paper introduces a shape memory alloy-restrainer-damper(SMA-RD) to protect multiple span continuous steel bridges from seismic loads. The type of bridges has only one fixed bearing condition on a pier and expansion bearings are located on the other piers and abutments. Due to this state and a big mass of the deck, these bridges are usually very vulnerable to column's damage on which fixed bearings are located and large deformation of abutments in passive action. Two types of SMA-RDs are developed, and their effect is inspected for protecting the bridges through seismic analyses. Conventional steel restrainer cables are also used to reduce the seismic vulnerability of the bridge and the results are compared to those of the SMA-RDs.

• Analytical Science and Technology
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• v.16 no.3
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• pp.212-217
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• 2003

The memory effect of silver and aqua regia in the vessel by their permeation was studied during the microwave digestion of samples under the operating conditions of high temperature and pressure. The extent of permeation in vessels with the solution containing silver 5 mg has been shown to be $0.97{\mu}g/mL$ for the digestion of $HNO_3$ solution and $0.47{\mu}g/mL$ for the digestion of oil sample under condition of MDS 180T program ($180^{\circ}C$, 220 psi).

• Journal of Life Science
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• v.26 no.2
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• pp.234-240
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• 2016

The Y-maze is widely used to test working memory in behavioral science. For this purpose, spontaneous alternation behavior is monitored, and an increased percentage of spontaneous alternation is regarded as enhanced working memory. However, in some cases, the percentage of spontaneous alternation does not accurately reflect the extent of working memory in rodents. To complement the short-comings of this measure, we developed a new method to evaluate working memory on the Y-maze. This is done by defining all spontaneous alternation cases and P_i, the probability that the rodent achieved spontaneous alternation from each alternation case. After all P_i-values acquired in each animal are summarized, the result is considered as entropy. To validate the new analytical method, mice were raised under either control or an enriched environmental condition for 10 weeks, and working memory behavior on the Y-maze was monitored. The results showed that the new analytical method successfully reproduced significance. In addition, the new method turned out to be more accurate than measurement of the percentage of spontaneous alternation, meaning that, to get higher entropy, alternation should be recorded in all arms and directions. Together, these data indicate that the new analytical method is a useful supplement to the method that compares the percentage of spontaneous alternation, and thus is a good tool with which to evaluate working memory in rodents.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.69-69
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• 2009

In other to progress better crystallization transition and long phase-transformation data of phase-change memory (PRAM), we investigated about the effect of Sb doping and Ag ions percolating into Ge-Se-Te phase-change material. Doped Sb concentrations was determined each of 10 wt%, 20 wt% and 30 wt%. As the Sb-doping concentration was increased, the resistivity decreased and the crystallization temperature increased. Ionization of Ag was progressed by DPSS laser (532 nm) for 1 hour. The resistivity was more decreased and the crystallization temperature was more increased in case of adding Ag layer under Sh-(Ge-Se-Te) thin film. At the every condition of thin films included Ag layer more stable states were indicated compare with just Sh-doped Ge-Se-Te thin films.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.213-216
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• 2007

In this paper. we study the controllability for the semilinear fuzzy integrodifferential equations with nonlocal condition and forcing term with memory in $E_N$ by using the concept of fuzzy number whose values are normal, convex, upper semicontinuous and compactly supported interval in $E_N$.